ANSH ENERGY SOLUTIONS PVT. LTD. [email protected] COMPREHENSIVE ENERGY AUDIT REPORT of 6.6 MW COGENRATION THERMAL CA
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ANSH ENERGY SOLUTIONS PVT. LTD. [email protected]
COMPREHENSIVE ENERGY AUDIT REPORT of 6.6 MW COGENRATION THERMAL CAPTIVE POWER PLANT CLIENT: M/S Magnum Ventures Ltd., Shaibabad
June, 2010
Audit conducted by:
ANSH ENERGY SOLUTIONS PVT. LTD., Gayatri Dham, Lower Bazar, Modinagar – 201204 (UP)
Auditor BEE Registration: EA-10465 (Anubhav Gupta) & EA3267(Anshul Singh Yadav) Report No. AESPL/10-11/AG/12
1
Contents Acknowledgement Audit firm and Audit Team Details List of Abbreviations Executive Summary Chapter 2: INTRODUCTION TO ENERGY AUDIT AND METHODOLOGY 2.1. Audit Objective and purpose of Energy Audit 2.2. Scope of Work 2.3. Methodology and approach followed 2.4. Time Schedule for Conducting the energy audit 2.5. Details of the Instruments used 2.6. Description of the Plant 2.7. Energy Consumption Profile and Energy Management System 2.8. Equipment and Major Areas for Energy Audit 2.10. List References Chapter 3: Boiler 3.1 BACKGROUND 3.2 Operational efficiency of the boiler 3.3 Blow down losses 3.4 Blow Down Rate Estimation 3.5 Boiler Water Treatment 3.6 Boiler blow down heat recovery applications 3.7 Energy Saving by Flash steam recovery 3.8 Energy Saving by Flue gas heat impingement on feed stock conveyor 3.9 Energy Saving by re‐insulation of damaged areas Chapter 4: Water Pumping 4.1 Background 4.2 Energy consumption pattern for pumps: 4.3 Observations & Recommendations Chapter 5: Turbine 5.1 Background 5.2 Turbine Efficiency evaluation 5.3 Effect of Steam inlet pressure 5.4 Effect of Steam inlet temperature 5.5 Effect of exhaust pressure/ vacuum Chapter 6: Condenser Cooling 6.1 Background 6.2 Cooling Tower 6.3 Observations 6.4 Conclusion Recommendation Chapter 7: Electrical Systems and Motors 7.1 Background 7.2 Transformers 7.3 Power Factor Analysis 7.4 Loading pattern of motors 7.5 Motor Efficiency Calculation 7.6 Harmonic Measurement 7.1 Power Supply Quality
ii iii iv v 1 1 1 1 2 2 2 3 5 6 7 7 10 10 14 14 16 17 18 19 19 19 20 22 22 22 24 25 26 28 28 28 29 30 32 32 32 33 34 36 38 40
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ACKNOWLEDGEMENT Investment Grade Energy Audit has been done with the objectives to identify & quantify the energy saving opportunities for 6.6MW Cogeneration Captive Thermal Power Plant of M/S Magnum Ventures Ltd., Shaibabad, Uttar Pradesh. We would like to thank Shri Pradeep Jain, MD, Magnum Ventures Ltd., Mr. Ritesh Jain for their giving us this opportunity and continuous support and encouragement during the course of Energy Audit. We also the commitment of Shri Pradeep Jain and his team towards cost reduction and energy conservation for betterment of the company and the environment. We extend our gratitude towards Mr. Anil Bana, Head Power Plant, and entire power plant team for their steadfast support extended to us during this study. We would like to convey our special thanks to field staff for their inputs. Energy Audit Team Anubhav Gupta Anshul Singh Yadav Vikram Pal Singh
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Audit Firm and Audit Team Details Ansh Energy Solutions Pvt. Ltd. is energy efficiency consultancy and practice areas are project feasibility, DPR preparation, Impact assessment studies, monitoring and verification assignments as independent evaluators, energy Audits, analyze the energy consumption and evaluate cost effective opportunities to save electricity and fuels. We also undertake advisory services for industries related to environmental aspects and works in the areas of Green Buildings, Climate change activities and Sustainable development. Ansh Energy Solutions Pvt. Ltd. is a professionally managed company with a team of full time engineering professionals and Energy Auditors who are available to help and address clients specific utility needs. Ansh Energy Solutions Pvt. Ltd. advices its clients on energy efficiency and energy conservation plans, which are of paramount importance to them. The areas of our expertise in this regard are: a)
Energy Audit
b)
End Use Efficiency Improvement Programmes
c)
Monitoring & Verification (M&V)
d)
Energy Conservation Management plan
Audit Team Anubhav Gupta, Director Ansh Energy Solutions Pvt. Ltd. Certified Energy Auditor from BEE having experience of umpteen project implementations including, manufacturing facility setup, power plant setups, refurbishing building envelopes, organization and coordination of various BEE seminars and workshops. By qualification a Chemical Engineer from IT‐BHU, MBA in Sales and Marketing and a certified Six Sigma Black belt he brings and all round experience of industry, institutions and academics together in one place. Anshul Singh Yadav Mechanical Engineer by basic qualification and MBA from the Management Development Institute (MDI), Gurgaon, Certified B.O.E (Boiler Operation Engineer First class proficiency) having over 12 years of hands on experience in in O&M of Power Plants and other utilities. Power sector experience, spans in the diverse aspects of energy business from Plant operations management, Maintenance planning, Fuel management and Strategic Planning, Plant Commissioning, etc. Vikram Pal Singh (PGDBM, BSc., DEE) is having 7 years of experience in energy audits, energy efficiency projects, project management and training. His area of interest is green buildings and CDM linked funding mechanism for Small size green projects. iii
Abbreviations ACs
Air Conditioners
BEE
Bureau of Energy Efficiency
CT
Cooling Tower
ECO
Energy Conservation Opportunity
EMP
Energy Management Plan
M3/hr
Cubic Meter Per Hours
FTL
Fluorescent Tube Light Lamp
HPSV High Pressure Sodium Vapour KVA
Kilo Volt Ampere
KWH
Kilowatt Hour
KVAH
Kilo Volt Amperes Hour
KVAr
Kilo Volt Amperes Reactive
KW
Kilo Watt
LPD Litres Per Day MW Mega Watt O&M
Operation and Maintenance
P.F
Power Factor
PV Photo Voltaic SPC
Specific Power Consumption
STC Standard Test Condition SWH Solar Water Heater SQ. M. Square Meter TR
Ton of Refrigeration
V Volt
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1. EXECUTIVE SUMMARY 1.1. Brief Company Profile: Magnum Ventures Ltd, one of the largest paper manufacturing mills of Northern India having installed capacity of 85000 TPA. This includes equal quantity of Cream wove Paper, Maplitho, Copier, and Coated Duplex Board. The Company is having large infrastructures 65000 Square Meter and Five Lacs Square feet Building Area in Sahibabad Industrial Area, Ghaziabad (U.P.). This energy audit study was carried out for 6.6MW thermal captive power plant of paper mill. This power plant was commissioned in the year 2004 as 4.4 MW unit and expanded to 6.6 MW in year 2008. Power Plant comprises of 31 Tph, Thermax make, Bi‐drum, natural circulation, under bed, balanced draft, atmospheric fluidisation bed combustion, bottom supported, and membrane wall construction type of a boiler. Two sets of Trevani make turbo generator with 1st Turbine is of 4.4 Mw extraction cum condensing type and 2nd Turbine is of 2.2Mw condensing Type and other power plant auxiliary and power distribution system.
1.2. Scope of the audit study: The main objective of this exercise is to carry out specific energy consumption analysis and make recommendations for reduction in auxiliary power, optimize specific fuel consumption and to achieve a reduction in recurring expenditure on energy to improve business viability by plugging the waste energy and through improvement in the operational and maintenance practices of the facility. Major areas covered under energy audit study of the Power Plant were Boiler and its auxiliaries, water pumping system, cooling towers, motors and electrical distribution system.
1.3. Time Schedule for Conducting the energy audit Field study – 4th June 2010 to 11th June 2010 Report Preparation – 12th June to 30th June
1.4. Energy Consumption and Energy Generation of the Plant: The average daily power production is 1,30,000 units and monthly power production average is of 39lacs unit of Power out of which 33.87lacs of unit is supplied to paper plant and rest 4.84 lac units per month is the Auxiliary Power Consumption, break‐up of this auxiliary power is graphically represented in following chart.
Auxiliary Power Components Pumps
Boiler Auxiliary 11%
25%
CT Fan
Others
5%
59%
Figure: Share of different equipments in Auxiliary Power Consumption
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The major part of this auxiliary power is being consumed by water pumping system, followed by Boiler auxiliaries like FD Fan, ID Fan, PA Fan and Coal handling system and Coal mill, around 11% of the auxiliary power is being consumed by cooling tower fans and rest 5% is consumed by remaining equipments and lighting load. Table: Monthly Fuel Consumption, Steam & Power Production and Supply position Month FEB March April May Total Coal Consumption in Ton
Cost of Coal (in Rs.) Total Steam Generation (in Ton) Steam supply to Plant (in Ton) Total Power Generated (KWh) Power Supply to Plant (Kwh) Fuel Cost per unit of Power (Rs/Kwh) Cost of steam (in Rs/ton) Aux Power Consumption Kwh Aux Power Consumption Ratio %
6368
6200
6238
4969
2,54,62,199
2,61,71,530
2,57,54,803
2,41,85,169
25,103
25,283
24,994
26,169
13,236
13,353
13,067
13,141
37,59,000
38,54,500
38,28,000
40,45,000
33,39,000
34,04,000
33,18,000
34,87,000
6.77
6.79
6.73
5.98
1014.31
1035.14
1030.44
924.19
420,000
450,500
510,000
558,000
8.95
8.56
7.51
7.25
Summary of the Baseline Energy Consumption 1 2 3 4 5 6 7 8 9 10 11
Average annual electricity production Average annual electricity supply to main Plant Average annual auxiliary power consumption Average annual steam generation Average Auxiliary Power consumption ratio Average annual Coal consumption for co‐generation Average heat rate of 4.4 MW turbine Average heat rate of 2.2 MW turbine Average Boiler Efficiency Average turbine cycle efficiency 4.4Mw Average turbine cycle efficiency 2.2Mw
4,64,59,500 kWh 4,06,44,000KWh 58,15,500KWh 3,04,647Ton 8.07% 71325ton 4700Kcal/kg 2800Kcal/kg 80% 18.3% 30.2%
1.5. Major observations: Â Boilers The method of performance assessment chosen for Boiler performance test is the indirect method of heat loss and boiler efficiency as per BIS standard 8753. The test method employed is based on abbreviated efficiency by loss method (or indirect method) tests, which neglects the minor losses and heat credits. The Boiler efficiency is observed as 80.91% against the 83 ±2% design efficiency, there is a margin of about 2‐3% improvement by various measures, which are largely O&E related and R&M related. About 1‐2% improvement is possible by various O&E related aspects such as providing improved insulation at furnace, APH, Economiser, manhole doors and by providing internal lining of fire proof cement on furnace doors. For further improvement in efficiency, R&M activities are required especially in the area of super heater so that design parameters of super heated steam can be
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achieved; in this regard detail techno economic and cost benefit analysis is being carried out in chapter on turbines. Overall boiler water, CBD & Steam water quality & chemistry is observed within the prescribed limit of OEM, however it was observed that parameters like O2, residual hydrazine, metal contents like copper and iron and conductivity are not being monitored on regular basis. CBD flow rate is observed in the range of 600‐900Liters/hr at temperature of 170 °C leaving scope for heat recovery through flash steam recovery system. Observed loss due to moisture in fuel is 0.86 % which can be brought down to a value of 0.20% detail is discussed in 3.8 sections.
 Water Pumping System Water pumping is vital energy consuming area in the power plant. Major pumps which were studied in this report are: ¾ ¾ ¾
Condensate Extraction pumps Boiler feed water pumps RO/DM water plant pumps
¾ ¾ ¾
Make‐up/transfer pump Cooling water circulation pumps Raw water pumps
Total approximate energy consumption of pumping system = 10754 Kwh per day Total auxiliary power consumption per day = 16200Kwh Almost two third of the auxiliary power is consumed by water pumping system. From the pump performance analysis based on the actual operating parameters we have observed efficiency of 4.4MW turbine condenser cooling water pumps less than 60% which is on lower side. There is no energy and flow meters installed for major pumps in the power plant
 Turbine The average heat rate of 4.4 MW turbine is observed as 4700Kcal/kg and for 2.2MW turbine is 2800Kcal/kg with turbine cycle efficiency of 18.3% and 30.2% respectively. In absence of performance GTR data it is difficult to identify deviation from that. It is also observed that steam generated in the boiler is of specification 65kg/cm2 and Temperature 445°C against the design temperature of 490°C ±5°C. An increase in inlet steam temperature, i.e., an increase in superheat at constant inlet pressure and condenser pressure gives a steady improvement in cycle efficiency and lowers the heat rate due to the increase in inlet temp and rising the inlet temperature also reduces the wetness of the steam in later section of the turbine and improves internal efficiency of the turbine. If the turbine inlet steam temperature is increased to 490°C ±5°C as per the design conditions then the heat energy input to the turbine will be increased and corresponding effect in cycle efficiency is achieved @ 5.5% to 6.5% reduction in specific steam consumption for same amount of power generated and turbine efficiency will improve by of 0.6% to 0.72%.
 Cooling Tower ¾ CT ‐1 range found to be 7.9 and CT‐2 range found to be 11.6 against design of 8 ¾ CT‐1&2 approach found to be 10.73 and 8.8 against design 4 indicates, poor heat transfer. ¾ CT‐1 &2, effectiveness found to be 42.40% and 56.86% against design 66.66%, which indicates poor heat transfer in CT. vii
¾ Power measurements indicate under loading on CT fan motors and power factor is in the range of 0.52 to 0.74. This is poor. ¾ In Cooling Tower ‐1, Fly ash & other foreign particles are presented in reasonable quantity at most of the places like lowers, frills etc.
¾ As per the water quality concerned, makeup water quality is very good, here the scaling chances in the system are very less but corrosion is taking place aggressively specially in MS pipelines.
¾ At some places in cooling water piping system corrosion observed due to which water leakage/seepage is existing.
¾ The corrosion in the system is suspected due to improper functioning of corrosion inhibitor treatment. As PH in circulating water is around 8.5, Zn as corrosion inhibitor will not work perfectly at higher PH. As Zinc will precipitate at higher PH & not inhibit the surfaces perfectly.
¾ Alkalinity in the makeup water is very less; treatment philosophy must be designed to take care of low alkalinity system to control corrosion.
 Electrical system and motors
¾ There is no sub metering of the transformers and major equipments. ¾ The cumulative transformation capacity is 8500 KVA for 4300 MW (5625 KVA) Alternator. ¾ The earthing pits for transformer are not adequately spaced. ¾ The overall power factor of the plant is being maintained at above 0.93 lagging, but the power factor of some of the individual feeders is below the satisfactory level.
¾ The motors of Main elevator 1&2, Reject elevator 1, Ash Handling Motor, and all cooling tower fans are operating at less than 60% of loading.
¾ The average total voltage harmonic distortion is 6.45%. ¾ The average total current harmonic distortion is 9.3%. ¾ The variation between the terminal voltage and specified voltage is under 5% which is a healthy sign.
1.6. Summary of recommendations and energy saving measures:
 Boilers To carry out modification and retrofit in super heater section of Boiler in order to achieve design parameter of main steam temperature of 490°C ±5°C will result in saving of 8 tons of coal per day and will reduce loading on Boiler by almost 1.8TPH, and improvement in boiler insulation will result in efficiency gain of 1% in boiler. The tentative investment for this work will be approximately INR 25,00,000/‐ and simple payback period of 58days. viii
Energy and Fuel saving by installing Flash steam recovery system for Boiler Continuous Blow down (CBD) the tentative saving of fuel through this measure should be 53580Kgs of coal and tentative investment for installing this system will be of INR 4,50,000/‐ and simple payback period of 557days. About 1‐2% improvement in boiler efficiency is possible providing improved insulation and re‐ insulation of damaged areas around, APH, Economiser, manhole doors, and at various other ducting points need to be redone and by providing internal lining of fire proof cement on furnace doors cost of this work is already taken in account in first point. The tentative saving from this step will be saving of 500Ton per annum of coal consumption on account of improved boiler efficiency even if 1% gain in boiler efficiency is achieved. Resulting into monetary saving of INR27,50,000/‐. Loss due to moisture in fuel is 0.86 % which can be brought down to a value of 0.20% by employing method for fuel moisture removal through piping a portion of flue gases at stack temperature on to the hooded conveyor of coal feed suing nozzles. Tentative investment for the duct and pipe work should be INR 3,00,000/‐ and overall boiler efficiency gain of 0.66% will result in annual saving of INR. 19,15,465/‐. Hence a simple payback period of 2 months.
 Water Pumping System By replacing cooling water circulating pumps with the energy efficient pumps which will have less specific energy consumption with respect to volume of water pumped and will give recurring energy saving of 190,895units per annum if motor is also replaced by energy efficient class of Motors and 113,880 units if only pump is replaced and existing motors are utilised. Payback period for proposed replacement of pumps in case‐1 is 87days and in case ‐2 is 146days. Quotation in this regard is attached as annexure for your reference. We also recommend installation of Flow and Energy meters for all major power consuming pumps and observe flow and power pattern on regular basis (Shift and Daily basis). So that pumps having deviation in specific power consumption can be identified by plant operation team.
 Cooling Tower For energy savings and better air flow consider replacement of Aluminum alloy cooling tower fan blades, with energy efficient FRP hollow fan blade. Estimated saving on account of each set of blades replaced will of 52560Kwh in case ‐1 when both Fan and motor are replaced and 26280 Kwh in case ‐ 2 when only fan blades are replaced with utilizing same motor. The investment for each set of blades is of INR 85,000/‐ and simple payback period on account of saving through reduced recurring energy consumption, for each set of fan blades replaced is 4months in case ‐1 when FRP Hollow Fan blades are installed with new high efficiency motor and 8 months in case‐2 if only new set of FRP Hollow Fan blades are installed with existing motor. Quotation in this regard is attached as annexure for your reference. Cooling tower fills needs to be checked for fill chocking and poor water distribution. Equal and uniform water flow to each cell to be ensured for proper distribution of water as this will improve effectiveness of Cooling Tower. Improved CT performance will allow to stop one CT fan during cold weather conditions. Monitor approach, effectiveness and cooling capacity for continuous optimisation efforts, as per seasonal variations as well as load side variations. A good chemical treatment with proper monitoring of the system will overcome all the water related problems in the system and the corrosion in the system is suspected due to improper functioning of corrosion inhibitor treatment. As PH in circulating water is around 8.5, Zn as corrosion inhibitor will
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not work perfectly at higher PH. As Zinc will precipitate at higher PH & not inhibit the surfaces perfectly, so consider organic treatment which will be a good option for corrosion control. Corrosion rack must be installed on monthly basis to check corrosion rate (mpy) in the system this system can be installed by cooling water treatment programme vendor at FoC.
 Electrical system and Motors The earthing pits provided for transformer are also not adequately spaced. This causes the earthing currents to either keep circulating in the system or is injected into the ground at various stages thus increasing heat losses. Due to this a major amount of energy which is produced is not recorded in the meters and a low efficiency is recorded. The proper earthing also enhances the protection relays to function as per the design parameters and will improve system safety and reliability. The installed capacitors need to be tested and relocated and some new capacitors need to added in the system so that the plant transmission and distribution losses are reduced. The expected annual savings from this measure should be approximately INR 36,44,160/‐. The tentative investment required for purchase of capacitors of 750Kvar is INR 3,59,950/‐ and simple payback period of 1.2 months. 12 motors are recommended to be changed with proper rating of energy efficient motors as suggested in following table: Table: Techno economic analysis for replacement suggested motors
The capital investment required for replacing the above mentioned motors is INR 6,77,700/‐ The cumulative tentative annual saving in energy is The cumulative monetary saving should be
681959 KWH
INR 34, 09,797/‐
The cumulative simple payback period is
3 months
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 Summary of overall saving The following Table presents the summary of various energy conservation measures suggested after conducting the Energy Audit of M/s Magnum Ventures Power Plant Shaibabad (UP)
SNO.
1 2 3
ENERGY SAVING PROPOSAL R&M in super heater section of boiler improving insulation for boiler and steam piping and by providing internal lining of fire proof cement on furnace doors Flash steam recovery system for Boiler CBD.
4
Energy Saving by Flue gas heat impingement on feed stock conveyor
5
Replacing cooling water circulating pumps with EE Pumps Case‐1 when motor+ pump both replaced Case‐2 only pump replaced
6
Replace CT Fan blade by EE FRP hollow fan Blades Case‐1 blade and motor both replaced Case‐2 only fan blade replaced
7
Adequately spacing earthing pits of transformer
9
Relocating and installing capacitors Replacing 12 motors with high efficiency proper size of motors
Total
8
ANNUAL SAVINGS
INVESTMENT REQUIRED
SIMPLE PAY BACK PERIOD
Rs.
Rs.
Months
1,56,58,500
25,00,000
2
27,50,000
as cost of insulation is considered in above
immediate
294,690
4,50,000
18.5
19,15,465
3,00,000
2
9,54,475
227,560
3
5,69,400
227,560
5
15,76,800
5,10,000
4
7,88,400
5,10,000
8
36,44,160
3,60,000
1.2
34,09,797
6,77,700
3
2,90,30,412
50,25,260
2.1
Nil
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2. INTRODUCTION TO ENERGY AUDIT AND METHODOLOGY 2.1. Audit Objective and purpose of Energy Audit The main objective of this exercise is to carry out specific energy consumption analysis and make recommendations for reduction in auxiliary power, optimize specific fuel consumption and to achieve a reduction in recurring expenditure on energy to improve business viability by plugging the waste energy and through improvement in the operational and maintenance practices of the facility.
2.2. Scope of Work The aim and scope of audit is to quantify the fuel and energy consumption of the facility. It further aims to identify the loss avenues in the systems and establish total and specific steam generation, boiler efficiency monitoring, load balancing, run‐ability optimization and achieving best possible fuel to steam ratio. The audit will thus cover parameter detection of: 1. Feed water inlet flow. 2. Blow Down flow estimation (If possible). 3. Inlet air temperature. 4. Temperature of exhaust to stack. 5. Feed water quality. 6. Cycle of concentration 7. Variance in phase loading of motors ACB’s and Transformer 8. Operation of motors 9. Losses due to poor capacitor behaviour or installation faults. 10. Load curves. The completion of audit will achieve identification of all types of boiler losses and possible ECOs (Energy Conservation Opportunities). It will highlight the efficiency improvement possibilities in motors, capacitors and voltage variations. The Audit has been done specifically for the steam generating unit, HVAC and Electricity Load Distribution. This inspection report reflects the conditions of the equipment at the time of the inspection only. Please note that equipment conditions change with time and use and the conditions noted in this report may change in appearance and severity as time progresses or with mishandling. Hidden or concealed defects cannot be included in this report. An earnest effort was made on our behalf to discover all fallacies; however in the event of an oversight no liability is acceptable. No warranty is either expressed or implied. This report is not an insurance policy, nor a warranty service.
2.3. Methodology and approach followed ANSH ENERGY SOLUTIONS PVT. LTD, conducted the investment grade energy audit study for the 6.6MW Cogeneration Captive Thermal Power Plant of M/S Magnum Ventures Ltd., Shaibabad, Uttar Pradesh, during June, 2010. As a part of the study, the energy audit team visited the Page 1
premises for undertaking performance assessment of various energy consuming equipments installed in the building using sophisticated energy audit instruments. The following methodology was adopted for successful conduct of the study: •
Monitoring of energy related parameters of various equipments using sophisticated and portable energy audit instruments.
•
Online measurement of operating data with various instruments.
•
Collection of details regarding electricity consumption in the past, maximum demand and power factor.
•
Discussion with concerned officials to take note of energy conservation activities already undertaken, if any.
•
Critical analysis of data collected during field visit. o Identification of opportunities having possible energy conservation potential and quantification of energy losses. o Identification of suitable measures for reducing energy consumption. o Preparation of financial analysis for recommended measures.
2.4.
Time Schedule for Conducting the energy audit Field study – 4th June 2010 to 11th June 2010 Report Preparation – 12th June to 30th June
2.5.
Details of the Instruments used Following major instruments were used during the field study and data collection 1. Power and Harmonics Analyser 2. Ultrasonic Flow Analyser 3. Contact type and non‐contact type infrared temperature sensors 4. Anemometer 5. Lux meter 6. Oxygen Probe and Flue gas analyser 7. Distance meter 8. Contact type digital tachometer
2.6.
Description of the Plant
Magnum Ventures Ltd. is a Paper Plant and Energy audit of its 6.6MW captive thermal power plant was carried out in the month of June 2010. The Magnum Ventures Power Plant is having following major Plant and Apparatus: Boiler: Thermax make, Bi‐drum, natural circulation, under bed, balanced draft, atmospheric fluidisation bed combustion, bottom supported, and membrane wall construction type of a boiler. Page 2
This boiler is normally operated @ 35‐37Tph Turbine: Plant is having two sets of turbo generator both of Trevani make 1st Turbine is of 4.4 Mw extraction cum condensing type and 2nd Turbine is of 2.2Mw condensing Type. Cooling Tower: Plant is having 2 Nos of Paharpur make 1200 m3/hr flow rate, induced draft cross flow type of cooling towers. Coal handling system: Magnum Ventures Power Plant receives coal through road and coal is stored in yard. The process flow diagram is represented as under:
Yard Coal Breaking Screen Conveyer Screen Coal Crusher Top Screw Main Elevator Screw Shoot Reject elevator
Bunker Coal Feeder
2.7.
Energy Consumption Profile and Energy Management System
Table: Monthly Fuel Consumption, Steam & Power Production and Supply position FEB March Month April Total Coal Consumption in Ton
Cost of Coal (in Rs.) Total Steam Generation (in Ton) Steam supply to Plant (in Ton) Total Power Generated (KWh) Power Supply to Plant (Kwh) Fuel Cost per unit of Power (Rs/Kwh) Cost of steam (in Rs/ton) Aux Power Consumption Kwh Aux Power Consumption Ratio %
May
6368
6200
6238
4969
2,54,62,199
2,61,71,530
2,41,85,169
25,103
25,283
2,57,54,803 24,994
13,236
13,353
13,067
13,141
37,59,000
38,54,500 34,04,000
38,28,000 33,18,000
40,45,000
33,39,000 6.77
6.79
6.73
5.98
1014.31 420,000
1035.14 450,500
1030.44 510,000
558,000
8.95
8.56
7.51
7.25
26,169
34,87,000 924.19
Page 3
30000 25000 20000 Steam Genration
15000
Steam Supply to Plant Feed Water Consumption
10000 5000 0 Feb/10
Mar/10
Apr/10
May/10
Figure: Feed water consumption, Steam Generation and Process Steam supply 45,00,000 40,00,000 35,00,000 30,00,000 25,00,000
Prower Genrated
20,00,000
Power Supplied to Plant Aux Power
15,00,000 10,00,000 5,00,000 0 Feb/10
Mar/10
Apr/10
May/10
Figure: Power Production, Power Supply to Plant and Auxiliary Power Consumption
Page 4
10 9 8 7 6 Auxilary Power Ratio %
5
Cost of Steam Rs./kg
4
Cost of Power Rs./Unit
3 2 1 0 Feb/10
Mar/10
Apr/10
May/10
Figure: Auxiliary Power ratio and cost of Steam & Power
Auxiliary Power Components Pumps
Boiler Auxiliary
CT Fan
Others
5% 11%
25%
59%
Figure: Share of different equipments in Auxiliary Power Consumption
2.8.
Equipment and Major Areas for Energy Audit
Major areas of energy audit in Magnum Ventures Power Plant were Boiler and its auxiliaries, water pumping system, cooling towers, motors and electrical distribution system. The objective of this audit was to carry out specific energy consumption analysis and make recommendations for reduction in auxiliary power.
Page 5
Energy Management Action Plan
2.9.
2.10. References ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾
The Steam and Condensate Loop Book – Best practice guide to energy saving solutions Power Plant Engineering – P.K. Nag BEE Manual on Energy Efficiency testing (Book 4) Perry’s Handbook of Chemical Engineers (2003) Spirax Sarco website www.emerson.com www.lenntech.com/boiler‐feedwater.htm MCT31 Harmonic Calculation software and Energy Box energy savings calculation software Online turbine performance analysis by Engineering toolbox Page 6
3. BOILER BOILER 3.1 BACKGROUND The boiler of Magnum Ventures Power Plant is used to produce steam at the high pressure and temperature required for the steam turbine that drives the electrical generator and extracted steam from extraction cum condensing turbine is supplied to process plant used in paper manufacturing process. The boiler has furnace, steam drum, mud drum, super heater coils, and economiser and air pre‐heaters. The air and flue gas path equipment include forced draft fan(FD), PA Fan, induced draft fan (ID), air preheaters (APH), boiler furnace, fan, fly ash collectors (electrostatic precipitators) and the flue gas stack. Brief schematic diagram of a typical system is given below. The brief specifications of this boiler are as follows: Particulars Make Type Capacity Main steam pressure Main steam temperature Boiler efficiency Super heater outlet flow Coal calorific value‐GCV Coal consumption Total combustion air LTSH outlet temperature Water‐economiser inlet temperature Water‐economiser outlet temperature Oxygen content at economiser outlet
Unit Tph Kg/cm2 °C % Tph Kcal/kg Tph Tph °C °C °C %
Details at Normal Continuous rating, NCR Thermax Water tube Bi‐drum 31 65kg/cm2 490 ± 5°C 83 ± 2 31 5680 (70%Coal and 30% Pet coke) NA 340 125 185 3.5
3.2 Operational efficiency of the boiler The boiler efficiency trial was conducted to estimate the operational efficiency under as run conditions. The efficiency evaluations, by and large, follows the loss components mentioned in the reference standards for boiler testing at site using indirect methods mentioned in BS 845:1987 as amended on date. The method of performance assessment chosen is the indirect method of heat loss and boiler efficiency as per BIS standard 8753. The test method employed is based on abbreviated efficiency by loss method (or indirect method) tests, which neglects the minor losses and heat credits. The major losses covered are: • • • •
Heat loss due to dry flue gas losses. Heat loss due to moisture in fuel Heat loss due to moisture in air. Heat loss due to hydrogen in fuel Page 7
• • •
Heat loss due to un‐burnt carbon in fly ash and bottom ash. Heat loss due to radiation to be assumed depending on emissivity of surface Unaccounted losses as declared by the boiler supplier
Following formula are used for estimation and calculation of Losses by indirect method:
a. Calculation for Dry Flue gases:
b. Heat loss due to dry flue gas This is the greatest boiler loss and can be calculated with the following formula:
Page 8
c. Loss due to un‐burnt carbon in ash, Luca Loss due to un‐burnt carbon in ash, Luca=
Luca= CV of carbon in Kcal/kg * [(C%FA*FAsh) + (C% BA* BAsh)]
GCV of Fuel Kcal/Kg Where C% BA ‐ % of Carbon in Bottom Ash C%FA ‐ % of Carbon in fly ash BAsh – Bottom ash quantity in Kg/Kg FAsh – Fly ash quantity in Kg/Kg
d. Loss due to moisture in fuel, Lmf Loss due to moisture in fuel, Lmf = M*[(0.45*(FGT‐ABT)) + 584] GCV of Fuel Where: M = is kg of moisture in 1 kg of fuel Cp = Specific heat of superheated steam in kCal/kg°C FGT = Flue gas temperature in °C ABT = Ambient temperature in °C 584 = Latent heat corresponding to partial pressure of water vapour
e. Loss due to hydrogen in fuel, Lhf Loss due to hydrogen in fuel, Lhf = 9*H2 * [(0.45 * (FGT‐ABT)) + 584] * 100 GCV Where H2 is kg of H2 in 1Kg of Fuel
f. Loss due to moisture in air, Lma
g.
Loss due to moisture in air, Lma = AAS*humidity*0.45*(FGT‐ABT)*100/GCV Where AAS = Actual mass of air supplied Humidity = Humidity of air in kg/kg of dry air Radiation and un‐accounted losses these losses considered as given in PG test/Design documents. Alternatively, the radiation losses can be estimated by measuring the surface temperatures and surface areas of the boiler section. Normally surface loss and other unaccounted losses are assumed based on type and size of the boiler as given below. For industrial fire tube / packaged boiler = 1.5 to 2.5% Page 9
For industrial watertube boiler = 2 to 3% For power station boiler = 0.4 to 1% These losses can be calculated if the surface area of boiler and its surface temperature are known as given below: LG = 0.548 X [{TS/55.55}4] + 1.957 X (Ts‐Ta)1.25 X √Vm Where LG = Radiation loss in watts/m2 Vm = Wind velocity in m/s Ts = Surface temperature (°K) Ta = Ambient temperature (°K)
3.3 Blow down losses : Dissolved salts find entry to the boiler through make‐up water which is continuously fed by the Boiler Feed Water pump ( bfw). In the boiler, there is continuous evaporation of water into steam. This leaves behind the salts in the boiler. Concentration of these salts, tend to increase in the boiler drum and starts precipitation after certain concentration level. Water from the drum should be blown down to prevent concentration of salts beyond certain limits. Since the water in the boiler drum is at a high temperature (equivalent to it's saturation temperature at boiler drum pressure), excess blow‐down will lead to loss of energy known as 'blow‐down losses'. Blow‐down rate reduces the boiler efficiency considerably as could be seen from the figure. Hence it is imperative that blow‐down rates are optimized, based on the hardness levels of boiler drum water which is a function of the operating pressure. In boiler operation practice, rate of blow down increases with steam pressure as the scaling tendency increases with high temperature because the hardness limits are very stringent. While figure gives an estimate of % blow down on losses, the same may be calculated from the hardness levels of make‐up water , flow rate ,steam generation rate and the hardness level of drum water (observed). Model given below could be used to determine the maximum limits of TDS (total dissolved solids) that could be tolerated in the boiler drum operating at various pressures. The correlation is based on American Boiler Manufacturers' Association code of practice. However, if the limits stipulated by the Boiler Designer are less than this value, the lower of the two must be taken as the tolerance limit.
Where TDS is the permissible Total Dissolved Solids in ppm at the boiler drum and Pr is the drum pressure in psig. The quantity of blow down to maintain the given status of boiler water in terms of TDS is determined by the material balance of solids across the boiler drum as given in the figure below.
3.4 Blow Down Rate Estimation : For estimating the boiler drum blow down rates, following nomenclatures are used. Let F = feed water in t/hr Cm = Concentration of TDS in make‐up water in ppm Cf = Concentration of TDS in feed water in ppm. Cb = Concentration of TDS in blow‐down water m = weight fraction of make‐up water in feed water. Page 10
Figure: Impact of Blow down Rate of fuel loss.
For establishing the blow‐down rate, a material balance on TDS is developed as shown. TDS balance: Wbd * Cb = F * m * Cm ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐i F = Ws + Wbd ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ii Therefore equation i may be written as Wbd * Cb = ( Ws + Wbd) * m * Cm ‐‐‐‐‐iii Page 11
If Cf is the TDS present in the combined feed water to the boiler, above equation may be written as Wbd * Cb = ( Ws + Wbd) * Cf ‐‐‐‐‐iv If more than the required quantity (i.e Wbd t/hr) is blown down, the excess quantity will result in lower boiler efficiency . Hence, it is imperative that boiler blow down rate is monitored continuously for achieving high boiler efficiency. An optimal blow down rate may be calculated taking into consideration the impact of high TDS on poor heat transfer vs boiler efficiency. Table : Data Sheet for Boiler efficiency evaluation Parameters Unit Duration 0900hrs to 1500hrs 07‐ 06‐2010 Average Unit Load % of NCR Coal Consumption Ambient parameters Dry bulb temperature Wet bulb temperature Relative humidity Moisture content in air Coal Parameters – Ultimate Analysis Carbon (C) Hydrogen (H) Sulphur (S) Nitrogen Oxygen Total moisture (H2O) Ash Gross calorific value Steam Parameters Main steam flow Main steam pressure Main steam temperature Air/Flue gas parameters (APH inlet) Oxygen content at inlet Flue gas temperature at inlet Air Temperature at inlet Air/Flue gas parameters (APH outlet) Flue gas temperature at outlet Oxygen content at outlet Air temperature at outlet Oxygen content at ID fan inlet Carbon content in fly ash Carbon content in bottom ash Bottom ash quantity (dry basis) Fly ash quantity (dry basis)
Design
As run data
Hr
Tph Kg °C °C % Kg/kg of air
% % % % % % % Kcal/kg Tph Kg/cm2 °C
58.96 7.16 0.56 2.02 9.88 7.43 13.99 5491 35.54 65.09 446.41
% °C °C
2.8 205.6 32
153.27 155 3.7 4 8 0.3 0.7
°C % °C % % % Kg/kg of Coal Kg/Kg of Coal
35.54 114.65% 35000 35 21.1 42.8 0.014
Page 12
The Boiler efficiency calculations are given in following table: Table: Boiler efficiency calculation for trial run period on 07th June 2010 by direct method Moisture Time Feed water Steam Fuel content Duratio supplied Produced Fired (kg) in Fuel n (ton) (ton) (%) (Hours)
S.No.
1
217
212
35000
5.8
4
Dry fuel weight available
Fuel Calorific value (kcal/kg)
Available energy (gcal)
Energy attained in steam at 65kg/cm2
Overall Efficienc y
38220.0
5491
209866.02
166976.50
79.56%
Table: Steam & Power Production, Plant fuel rate and Boiler efficiency calculations Date
Feed water Steam Coal consumption Production Consum (ton) (ton) ption
Power Generated (units) 4.4MW 2.2MW
Total
Overall plant fuel rate kg/kWh
Boiler Efficiency
06‐06‐2010 914 890 139 91000 44000 135000 1.03 79.25% 07‐06‐2010 872 847 136 93000 37000 130000 1.05 77.08% 08‐06‐2010 916 893 141 99000 38000 137000 1.03 78.39% 09‐06‐2010 822 796 125 89000 34000 123000 1.02 78.82% 10‐06‐2010 927 900 142 101000 39000 140000 1.01 78.44% Table: Efficiency evaluation of Boiler by indirect method during trial run period on 07th June 2010 Design Actual % Parameters Unit Value Value Deviation Load Ton Fuel GCV Kcal/Kg 5491 loss due to dry flue gases, Ldfg % 5.52 Loss due to Hydrogen in Fuel % 7.49 Loss due to moisture in air % 0.15 Loss due to unburnt carbon in ash, % 0.67 Luca Loss due to moisture in fuel, Lmf % 0.86 Radiation Loss % 2.2 Unaccounted loss and % Na manufacturers margin Heat loss due to blowdown % 1.4 Loss due to furnace door draft % 0.8 Total Loss 19.09% Boiler Efficiency (1‐Total Loss) % 83 ± 2% 80.91% 0.09% The heat loss profile covering losses through unburnt in ash, sensible heat loss in flue gases, moisture in combustion air, loss due to presence of hydrogen and moisture in coal, radiation and unaccounted loss, are represented in above table. Above trial data is average value during 30 min. interval. It may be observed that as against 83% design efficiency, there is a margin of about 2‐3% improvement by various measures, which are largely O&E related and R&M related. About 1‐2% improvement is possible by various O&E related aspects such as providing improved insulation at furnace, APH, Economiser, manhole doors and by providing internal lining of fire proof cement on furnace doors. For further improvement in efficiency, R&M activities are required specially in the Page 13
area of super heater so that design parameters of super heated steam can be achieved, in this regard detail techno economic and cost benefit analysis is being carried out in chapter on turbines.
3.5 Boiler Water Treatment Water quality influences the performance of boiler internals. As energy auditors we observed the present water treatment parameters pertaining to: Type and rated capacity Operating capacity of the internal and external treatment methods Water quality parameters Control of blow down (CBD & IBD) Condensate polishing Table: DM water, feedwater, CBDand Steam parameters as on 04th June 2010 Particulars Unit MB Feed water CBD Ph 6.5 9.0 9.5 P Alk ppm Nil 1.0 6.0 T Alk ppm 3.0 5.0 12 Total Hardness ppm Nil nil Nil Chlorides ppm 4.0 4.2 6.3 TDS ppm 0.0 2.6 23.3 : DM water, feedwater, CBDand Steam parameters as on 01st June 2010 Particulars Unit MB Feed water CBD Ph 6.5 9.0 9.5 P Alk ppm nil 1.0 5.0 T Alk ppm 4.0 5.0 10 Total Hardness ppm nil nil nil SiO2 ppm ‐ 0.02 1.3 Chlorides ppm 4.2 4.2 6.3 TDS ppm 0.0 2.6 23.3
Steam 8.5 1.0 4.0 nil 4.0 1.6
Steam 8.5 1.0 4.0 nil 0.02 3.5 1.6
Observations ¾
¾
¾
Overall boiler water, CBD & Steam water quality & chemistry is observed within the prescribed limit of OEM, however it was observed that parameters like O2, residual hydrazine, metal contents like copper and iron and conductivity are not being monitored on regular basis. CBD flow rate is observed in the range of 600‐900Liters/hr at temperature of 170 °C leaving scope for heat recovery through flash steam. The amount of flash steam which can be released by the CBD water blow down flow rate of 600Kg/hr at 1 bar g would be 199.3 kg/h of flash steam. This flash steam recovery will reduce load on DM plant by 200Kg/hr as pure water can be recovered by installing Boiler continuous blow down (CBD) heat recovery system.
3.6 Boiler blow down heat recovery applications Continuous blow down of boiler water is necessary to control the level of TDS (Total Dissolved Solids) within the boiler. Continuous blow down lends itself to the recovery of the heat content of the blow down water and can enable considerable savings to be made.
Page 14
Boiler blow down contains massive quantities of heat, which can easily be recovered as flash steam. After it passes through the blow down valve, if the lower pressure water flows to a flash vessel. At this point, the flash steam is free from contamination and is separated from the condensate, and can be used to heat the boiler feed tank/condensate tank or can be supplied back to Deaerator tank (see Figure for a typical application of flash steam recovery system). The residual condensate draining from the flash vessel can be passed through a plate heat exchanger in order to reclaim as much heat as possible before it is dumped to waste. Up to 80% of the total heat contained in boiler Continuous Blow Down can be reclaimed in this way.
Figure: Typical heat recovery system from boiler blow down Consider the CBD water and process plant condensate is being discharged to a flash vessel pressurized at 1 bar g and at temperature of 170°C. If the return line were connected to a vessel at a pressure of 1 bar g, then it could be seen from steam tables that the maximum heat in the condensate at the trap discharge would be 505 kJ/kg and the enthalpy of evaporation at 1 bar g would be 2201 kJ/kg. The proportion of the condensate flashing off at 1 bar g can then be calculated as follows: Heat in condensate at 4 bar g = 640 Kj/kg At 1 bar g saturated condensate can only hold = 505 Kj/Kg Surplus heat in saturated condensate at 1 bar g = 135 Kj/kg Heat in steam at 1 bar g = 2201 Kj/kg Proportion of flash steam = 135 Kj/kg/ 2201 Kj/Kg Proportion of flash steam from the condensate = 0.061 (6.1%) In this case, if the equipment using steam at 4 bar g were condensing 15000 kg/h of steam, then the amount of flash steam released by the condensate at 1 bar g would be 0.061 x 15000 kg/h = 919.5 kg/h of flash steam. Therefore, the amount of flash steam produced can depend on the type of steam trap used, the steam pressure before the trap, and the condensate pressure after the trap. Similarly for CBD water flash recovery Page 15
The proportion of the condensate flashing off at 1 bar g can then be calculated as follows: Heat in condensate at 64 bar g = 1236 Kj/kg At 1 bar g saturated condensate can only hold = 505 Kj/Kg Surplus heat in saturated condensate at 1 bar g = 731 Kj/kg Heat in steam at 1 bar g = 2201 Kj/kg Proportion of flash steam = 731 Kj/kg/ 2201 Kj/Kg Proportion of flash steam from the condensate = 0.332 (33.2%) In this case, if the CBD water at 64 bar g were released @ 600 kg/h of saturated water, then the amount of flash steam released by the condensate at 1 bar g would be 0.332 x 600 kg/h = 199.3 kg/h of flash steam. Flash vessels are used to separate flash steam from condensate. Following Figure shows a typical flash vessel constructed in compliance with the European Pressure Equipment Directive 97/23/EC. After condensate and flash steam enter the flash vessel, the condensate falls by gravity to the base of the vessel, from where it is drained, via a float trap, usually to a vented receiver from where it can be pumped. The flash steam in the vessel is piped from the top of the vessel to any appropriate low pressure steam equipment.
Figure: A typical flash vessel
3.7 Energy Saving by Flash steam recovery Energy and Fuel saving through Flash steam recovery can be calculated as under:
Page 16
The heat requirement for increasing the temperature of 199kg of cold make‐up water by 140°C (fresh make up water temperature as 30°C and flash steam temperature of 170°C), by using following Equation Where: Q m cp ΔT
= = = =
Quantity of energy (kJ) Mass of the substance (kg) Specific heat capacity of the substance (kJ/kg °C) Temperature rise of the substance (°C)
In our case m is 199Kg; ΔT is the difference between the cold water make‐up and the temperature of returned flash steam from CBD water; cp is the specific heat of water at 4.19 kJ/kg °C. 199 kg x 4.19 kJ/kg °C x 140°C = 116733.4 kJ/kg Basing the calculations on an average for a plant in operation 8 400 h/year (350 days of operation), the energy required to replace the heat in the make‐up water is: 116733.4 kJ/kg x 8 400 h/year = 980 560.56 GJ/year Or 27900Kcal/kg X 8400 h/year = 234360 Gcal/year If the average boiler efficiency is 81%, the energy supplied to heat the make‐up water is: 234360 Gcal/year 0.81
289333.33 GCal/year
Amount of Fuel saved considering calorific value of coal as 5400Kcal/kg = 53580Kgs Cost of fuel saved per year considering cost of coal as Rs 5500 per ton – Rs. 294,690/‐ Cost of installing flash heat recovery system for continuous blow down shall be Rs 4.5 lacs Simple payback period is 1.53 years or (557 days/ 80 week)
3.8 Energy Saving by Flue gas heat impingement on feed stock conveyor Observed loss due to moisture in fuel is 0.86 % which can be brought down to a value of 0.20%. The easiest method for fuel moisture removal is piping a portion of flue gases at stack temperature on to the hooded conveyor of coal feed suing nozzles. A picture for example of fuel heating and moisture removal is attached below. The saving of 0.66% amounts to ‐ 0.66% x Rs. 24185169 (May Consumption) = Rs. 1,59,622 Thus the annual savings are 1,59,622 x 12 = Rs. 19,15,465/‐ Tentative investment for the duct and pipe work = Rs. 3,00,000/‐ Hence a simple payback period = (300000/1915465) x 12 = 1.87 Say 2 months
Page 17
3.9 Energy Saving by re‐insulation of damaged areas The damaged insulation at Economizer and APH ducts and at various other ducting points need to be redone. The reduction in radiation loss will be from 2.2% to standard 1% Thus the savings will be = 1.2% i.e. 1.2% x Rs. 24185169 (May Consumption) = Rs. 290222 monthly or Rs. 34,82,664/‐ annually. The cost for insulation work is Approx. 10 lacs and the simple payback comes to 10/34.82 = 3.44 or say 4 months. The final savings are as below: a) b) c) d)
Savings due to Blowdown flash heat recovery = 0.4% Savings due to Moisture in fuel = 0.66% Savings due to radiation reduction = 1.2% Savings due to Furnace door drafts = 0.6%
Hence the boiler efficiency will be improved in total by 2.86%
Page 18
4. WATER PUMPING
Water Pumping
4.1
Background Water pumping is vital energy consuming area in the power plant. Major pumps in Magnum Ventures Power Plant are: Condensate Extraction pumps Boiler feed water pumps RO/DM water plant pumps Make‐up/transfer pump Cooling water circulation pumps Raw water pumps
4.2
Energy consumption pattern for pumps: The daily energy consumption by pumping system is as follows:
Sno.
Equipment Submersible pump 1 Submersible pump 2 Submersible pump 3 HP 2‐1 RO HP 1‐1 RO HP 1‐2 RO HP 2‐2 RO Boiler Feed Pump 1 Boiler Feed Pump 2 2.2 MW CT Pump 1 CT Pump 2 CT Pump 3 CEP 1 CEP 2 4.4 MW CT Pump 1 CT Pump 2 CT Pump 3 CEP 1 Total
Instantaneous KW
Daily Consumption KWh
24.31 15.3 18.8 15.34 15.8 10.96 10.3 160 148
583 367 451 276 284 197 185 3840 3552
41.8 42.6 10.1
1003 1022 0 242 0
50.3 46.6 0 11 Kwh/Day
1207 1118 0 264 10754
Total energy consumption of pumping system = 10754 Kwh per day Total auxiliary power consumption per day = 16200Kwh Page 19
Almost two third of the auxiliary power is consumed by water pumping system. Table: Design, operating parameters and efficiency of pumps Measured Paremeters
Pump Specification Description of Pump
Power input by Motor
Motor
Pump
Make
Q(flow) in m3/hr
Head in Meter
Motor KW
RPM
Flow
Pressure in kg/cm2
BFP-1
KSB
40
850
137
2980
42
80
160
88.3%
64.5%
BFP-2
KSB
40
850
137
2980
40
85
148
90.5%
68.9%
Transfer Pump
Grundfos
45
50.7
11
2900
24.5
5.5
6.5
90.0%
62.5%
CEP-1 (4.4 MW)
KSB
12.1
89
12.1
2900
12.8
8.8
9
85.9%
52.1%
CEP-1 (2.2 MW)
Sulzer
13.5
90
9.7
2920
13.6
8.8
8.1
84.9%
55.8%
RO HP Pump-1
Grundfos
21
207
15
2920
20
14
15.8
87.2%
65.1%
IST RO HP Pump-3
Grundfos
21
207
16
2920
19
14
15.34
87.2%
63.9%
2nd RO HP Pump-2
Grundfos
17
135.6
11
2920
17
13
10.96
84.2%
65.0%
2nd RO HP Pump-3
Grundfos
17
135.6
11
2920
17
13
10.3
86.5%
67.3%
CT Pump-1 (4.4)
NA
NA
NA
NA
1440
400
2.2
50.3
85.8%
55.3%
CT Pump-2 (4.4)
NA
NA
NA
NA
1440
390
2.2
46.6
83.9%
58.6%
CT Pump-1 (2.2)
NA
NA
NA
NA
1440
380
2.2
41.8
73.3%
74.0%
CT Pump-2 (2.2)
NA
NA
NA
NA
1440
390
2.2
42.6
69.4%
78.7%
32
2
3.6
82.0%
61.7%
IST
Raw Water Pump-1
Discharge
Efficiency efficiency
in KW
Observation From the pump performance analysis based on the actual operating parameters we have observed efficiency of 4.4MW turbine condenser cooling water pumps on lower side. There is no energy and flow meters installed for major pumps In case of pumping system pump efficiency as per industry standards is considered as Normal ‐ 60 – 75% Best ‐ 78 ‐‐ 80% (upto 89% efficiency in case of horizontal split casing pumps) Worst ‐ 30 – 60% (Reference: CII‐LM Thapar Centre for Competitiveness for SMEs)
Recommendation We suggest replacing cooling water circulating pumps with the energy efficient pumps which will have less specific energy consumption and will give recurring energy saving of 190,895units if motor is also replaced by energy efficient class of Motors and 113,880 units if only pump is replaced and existing motors are utilised. Payback period for proposed replacement of pumps in case‐1 is 87days and in case ‐2 is 146days. We also recommend installation of Flow and Energy meters for all major pumps and observe flow and power pattern on regular basis (Shift and Daily basis). So that pumps having major power consumption can be identified. Page 20
Table: Saving potential and cost analysis for replacing circulating cooling water pumps with new energy efficient pumps
Parameters Pump Specifications No. of Pumps Pump Type Capacity Total Head Efficiency BKW at Shaft Required Motor Energy Consumption
Present Pumping System 2+1 and 2+1 Hori NA 20mtrs NA 45KW 41‐51Kw
Proposed Pumping System Case‐1 Case ‐2 With New Motor With existing motor Replace 2+2 by EE Pumps & Replace 2+2 Pumps only and EE Motors utilise existing motors Hori. B.P.O. Hori. B.P.O. 450m3/hr 450m3/hr 20mtrs 20mtrs 86% 86% 22.57 22.57 30 KW 30 KW 25.2KW at 80% loading and With present motor efficiency projected motor load 30 to 35 KW 95% efficiency motor
Energy consumption per 1128KWh 605Kwh 816Kwh day Annual Energy Saving Nil 190895Kwh 113880Kwh Saving in recurring Energy cost per annum Nil 9,54,475 INR 5,69,400 INR (@Rs5/Kwh) Cost of New Pumps 227,560/‐ INR for 4 Pumps @56890.00 each pump Simple pay back 3months (87Days) 5months (146Days) Note: Quote for new energy efficient pump is attached as annexure for your reference. Cost of motor is not considered in above scenario as it is worked out in Electrical & motor chapter. For the pump used in above example calculating power requirement . 3 450m /hr = 125l/s .
=21.38Kw (approx) Therefore Motor input power will be 21.38/0.95 = 22.51Kw Therefore annual running cost = 22.51Kw x 24h x 350 day x Rs 5/Kwh = INR 945,420/The approximate costs to an industrial purchaser are as follows: Bare shaft pump alone INR 56,000/Or Pump + Motor INR 1,37,000/Running costs for pump lifetime say 20 years = INR 1,89,08,400/- at present energy cost. Comparing above costs with the running costs of pump during lifetime Initial capital cost of pump + motor Maintenance Costs
- 1.5% - 2.5%
Running costs
- 96%
The main conclusion to be drawn from these figures is that running costs far outweigh capital costs and should be considered far more important when specifying new equipment. Pumps and motors should be sized according to short‐term requirements. If they are oversized to cater for potential increase in water demand, then running cost, as well as capital cost, will be elevated. The pumps and their operation should be well matched to the water requirements of the process, and it important to maintain pump operation at high efficiencies for the economy of production.
Page 21
5. TURBINE TURBINE 5.1 Background Steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it to useful mechanical work. In Magnum Ventures Power Plant 2 steam turbines 1st is of 4.4MW Extraction cum condensing and 2nd is of 2.2MW condensing type. Following is the process flow diagram
h 1
Boiler
G
4.4 Mw Extraction cum Condensing Turbine
H3
h2 Extraction at
4kg/cm2 and 210°C
2.2Mw Condensing Turbine
G
Figure: Process Flow Diagram for Magnum Ventures Cogeneration Power Plant
5.2 Turbine Efficiency evaluation Turbine heat rate can be calculated as Turbine heat rate (Kcal/Kwh) = mass flow rate of Steam(in kg/hr) X (h1‐ h4) P(Average power generated in KW) where h1 = enthalpy of inlet steam in kCal/kg h2= enthalpy of extracted steam in kCal/kg h3= enthalpy of steam at condenser in kCal/kg h4 = enthalpy of feed water in kCal/kg Turbine cycle efficiency can be calculated as Turbine cycle efficiency % = __860 X 100____ Turbine heat rate Page 22
4.5MW
2.2 MW
Total
Steam Extraction
4.5MW
2.2 MW
Total
Coal Consumption
Overall plant fuel rate kg/kWh
4.5MwTurbine Heat Rate (Kcal/Kg)
2.2Mw Turbine Heat Rate (Kcal/Kg)
4.5Mw Turbine cycle efficiency %
2.2MW Turbine cycle efficiency %
Table: Monthly average of Steam Supply, Power Generation, Heat rate and Turbine cycle efficiency
FEB
679
180
859
472
94179
40071
3759000
227
1.70
4780
2980
18.0%
28.9%
March
654
160
814
448
91259
38222
129481
205
1.59
4753
2772
18.1%
31.0%
April
644
154
798
436
91167
36433
127600
208
1.64
4683
2815
18.4%
30.6%
May
646
164
811
424
92323
38161
130484
160
1.24
4638
2846
18.6%
30.2%
Month
Steam supply to Turbines
Power Generated
Table: Monthly Fuel Consumption, Steam & Power Production and Supply position FEB March Month April Total Coal Consumption in Ton
Cost of Coal (in Rs.) Total Steam Genration (in Ton) Steam supply to Plant (in Ton) Total Power Genrated (KWh) Power Supply to Plant (Kwh) Fuel Cost per unit of Power (Rs/Kwh) Cost of steam (in Rs/ton) Aux Power Consumption Kwh Aux Power Consumption Ratio %
May
6368
6200
6238
4969
2,54,62,199
2,61,71,530
2,41,85,169
25,103
25,283
2,57,54,803 24,994
13,236
13,353
13,067
13,141
37,59,000
38,54,500 34,04,000
38,28,000 33,18,000
40,45,000
33,39,000 6.77
6.79
6.73
5.98
1014.31 420,000
1035.14 450,500
1030.44 510,000
924.19 558,000
8.95
8.56
7.51
7.25
26,169
34,87,000
Observations: It was observed that steam generated in the boiler is of specification 65kg/cm2 and Temperature 445°C against the design temperature of 490°C ±5°C. An increase in inlet steam temperature, i.e., an increase in superheat at constant inlet pressure and condenser pressure gives a steady improvement in cycle efficiency and lowers the heat rate due to the increase in inlet temp and rising the inlet temperature also reduces the wetness of the steam in later section of the turbine and improves internal efficiency of the turbine. If the turbine inlet steam temperature is increased to 490°C ±5°C as per the design conditions then the heat energy input to the turbine will be increased and corresponding effect in cycle efficiency is achieved as illustrated in following table:
Page 23
Table: illustration of impact of inlet steam temperature on operating conditions and cycle efficiency
Present Case in which Steam at 65kg/cm2 and 445 °C
Projected Case If Steam Temp is 485°C and Pr. 65kg/cm2
Enthalpy of input steam at 445°C and 65kg/cm2
785.37kcal/kg
Enthalpy of input steam at 485°C and 65kg/cm2 is 808.102kcal/kg
Saturation temp °C
280.86 °C
280.86°C
Enthalpy :@ saturation temperature
664.17 kcal/kg
664.17 kcal/kg
Enthalpy @ outlet conditions : 647 mmhg vacuum = 113 mmhg pressure absolute
= 620.5 kcal/kg
620.5 kcal/kg
Saturation temperature =
53.5 oC
53.5 oC
Net energy input = steam rate (kg/hr) *Δ Enthalpy kcal /hr
=35000 * (785.37 – 620.5)
35000 * (808.10 – 620.5)
=5770450 Kcal/hr
6566000 Kcal/hr
= (445 – 53.5) x 100 (445+273) = 54.53%
= (485 – 53.5) x 100 (485+273) = 56.93%
Carnot cycle efficiency
Steam Turbines are a major energy consumer. Optimising process operating conditions can considerably improve turbine water rate, which in turn will significantly reduce energy requirement. Various operating parameters affect condensing and back pressure turbine steam consumption and efficiency.
5.3 Effect of Steam inlet pressure Steam inlet pressure of the turbine also effects the turbine performance. All the turbines are designed for a specified steam inlet pressure. For obtaining the design efficiency, steam inlet pressure shall be maintained at design level. Lowering the steam inlet pressure will hampers the turbine efficiency and steam consumption in the turbine will increase. Similarly at higher steam inlet pressure energy available to run the turbine will be high, which in turn will reduce the steam consumption in the turbine. Figure ‐ a & b represents the effects of steam inlet pressure on steam consumption and turbine efficiency respectively, keeping all other factors constant for the condensing type turbine.
Fig a: Effect of steam pressure on steam consumption in condensing type turbine
Fig b: Effect of steam pressure on turbine efficiency in condensing type turbine
Page 24
Figure ‐ a & b indicates that increase in steam inlet pressure by 1 kg/cm2 in condensing type turbine reduces the steam consumption in the turbine by about 0.3 % and improves the turbine efficiency by about 0.1 % respectively. In case of back pressure type turbine increase in steam inlet pressure by 1 kg/cm2 reduces the steam consumption in the turbine by about 0.7 % and improves the turbine efficiency by about 0.16 % as shown in figure ‐ c & d. Improvement in back pressure type turbine is more than the condensing type turbine.
Fig c : Effect of steam pressure on steam consumption in back pressure type turbine
Fig d: Effect of steam pressure on turbine efficiency in back pressure type turbine
5.4 Effect of Steam inlet temperature Enthalpy of steam is a function of temperature and pressure. At lower temperature, enthalpy will be low, work done by the turbine will be low, turbine efficiency will be low, and hence steam consumption for the required output will be higher. In other words, at higher steam inlet temperature, heat extraction by the turbine will be higher and hence for the required output, steam consumption will reduce. Figure ‐ e & f represents the effects of steam inlet temperature on steam consumption and turbine efficiency respectively, keeping all other factors constant for the condensing type turbine.
Fig e:Effect of steam temperature on steam consumption in condensing type turbine
Fig f: Effect of steam temperature on turbine efficiency in condensing type turbine
Page 25
Figure ‐ e & f indicates that increase in steam inlet temperature by 10 deg C in condensing type turbine reduces the steam consumption in the turbine by about 1.1 % and improves the turbine efficiency by about 0.12 % respectively.
Fig g : Effect of steam temperature on steam Fig h: Effect of steam temperature on turbine consumption in back pressure type turbine efficiency in back pressure type turbine In case of back pressure type turbine increase in steam inlet temperature by 10 deg C reduces the steam consumption in the turbine by about 1.5 % and improves the turbine efficiency by about 0.12 % as shown in figure ‐ g &h. Improvement in back pressure type turbine is more than the condensing type turbine.
5.5 Effect of exhaust pressure/ vacuum Higher exhaust pressure/ lower vacuum, increases the steam consumption in the turbine, keeping all other operating parameters constant. Exhaust pressure lower than the specified will reduce the steam consumption and improves the turbine efficiency. Similarly exhaust vacuum lower than the specified , will lower the turbine efficiency and reduces the steam consumption. Figure 2a & 2b represents the effects of exhaust vacuum on steam consumption and turbine efficiency respectively, keeping all other factors constant for the condensing type turbine. Figure 2a & 2b indicates that improvement in exhaust vacuum by 10 mm Hg, reduces the steam consumption in the turbine by about 1.1 %. Improvement in turbine efficiency varies significantly from 0.24 % to 0.4 %.
Fig 2a : Effect of exhaust vacuum on steam consumption in condensing type turbine
Fig 2b : Effect of exhaust vacuum on turbine efficiency in condensing type turbine Page 26
The above figures also demonstrate that considerable in cycle efficiency with decrease of condenser pressure. Such decrease is mainly depending on the available cooling water temperature and thus on climatic condition of a place. Taking the current steam condition and projected steam condition the efficiency gain is projected in following tables: Table: impact of steam temperature on 2.2 MW turbine efficiency Rated Power 2200 kW 2200 kW HP Steam Pressure
66 bar abs
66 bar abs
HP Steam Temperature
445 °C
485 °C
Exhaust Steam Pressure
0.15 bar abs
0.15 bar abs
Full Load Isentropic Efficiency
76.0 %
80.1 %
Full Load Specific Steam Consumption
4.3 kg/kWh
4.1 kg/kWh
Source: Sugar Engineers Engineering Data software
5.6 Conclusion: On the basis of above assumptions and theory if the turbine inlet steam temperature is maintained @ 485°C with keeping all other conditions & factors constant then the projected gain will be: Table: cost benefit analysis for suggested modification to achieve desired steam temperature Present average steam demand per day 850 ton per day Improved steam temperature will reduce steam consumption 803 ton per day by 5.5%, projected steam demand Saving in steam for same output 46.75 ton per day quantity of coal saved due to avoided steam generation 7.8 ton per day Cost of coal saved 42900 Rs per day Annual fuel saving 2847 ton Annual Saving 1,56,58,500 Tentative investment on boiler modification Rs.25,00,000 Simple Payback period 60 days
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6. CONDENSER COOLING
6.1
Background
In power plant, the cooling tower, water pumping and condenser are involved in condensing the exhaust steam from a steam turbine and transferring the waste heat to the atmosphere. 6.2
Cooling Tower
In the following table specifications of cooling tower are given Table: Cooling tower specifications Cooling Tower‐1 Cooling Tower‐2 Particulars Design Operating Design Operating Make & Model Type No of Cells Rated flow Fill Details No of CT fans CT fan KW No. Of blades per fan Dia of Blade assembly Blade material Hot water inlet temp °C Cold water outlet temp °C Wet bulb temp. °C
Paharpur 452‐293 Induced Draft Cross Flow 3 3 1200 800 Treated wood splash bars 3 3 30 15.78/14.35/14.7 9 9 144” 144” Cast Al alloy Cast Al alloy 40 45 32 36.9 28 26.2
Paharpur 452‐293 Induced Draft Cross Flow 3 3 1200 750 Treated wood splash bars 3 3 30 14.15/11.3/12.1 9 9 144” 144” Cast Al alloy Cast Al alloy 40 46.8 32 35 28 25.7
Cooling Tower Performance
Figure: Range and Approach
Page 28
The important parameters, from the point of determining the performance of cooling towers, are: Range ‐ is the difference between the cooling tower water inlet and outlet temperature. Approach ‐ is the difference between the cooling tower outlet cold water temperature and ambient wet bulb temperature. Although, both range and approach should be monitored, the 'Approach' is a better indicator of cooling tower performance. Cooling tower effectiveness (in percentage)‐ is the ratio of range, to the ideal range, i.e., difference between cooling water inlet temperature and ambient wet bulb temperature. Cooling capacity ‐ is the heat rejected in kCal/hr or TR, given as product of mass flow rate of water, specific heat and temperature difference.
Table: Cooling tower operating and efficiency calculations Parameter Inlet Cooling Water Temperature °C Outlet Cooling Water Temperature °C Air Wet Bulb Temperature near Cell °C Air Dry Bulb Temperature near Cell °C Number of CT Cells on line with water flow Total Measured Cooling Water Flow m3/hr CT Range CT Approach % CT Effectiveness = Range ___X 100 (Range + Approach) Rated % CT Effectiveness (Design Data)
Cooling Tower‐1 45 36.9 26.27 38.33 4 800 8.1 10.63
Cooling Tower‐2 46.8 35 25.7 38.8 4 770 11.8 9.3
Cooling Tower‐1 44.9 37 26.27 38.33 4 7.9 10.73
Cooling Tower‐2 46.1 34.5 25.7 38.8 4 11.6 8.8
43.25%
55.92%
42.40%
56.86%
66.66%
66.66%
66.66%
66.66%
Present water quality of makeup water & circulating water for cooling tower at Magnum Ventures, (Power Plant) Sahibabad are given in following table Table: Water Chemistry of Cooling Tower make‐up and circulating water Parameters PH P‐ Alkanity M‐ Alkanity Chloride TDS Total Hardness
Makeup water 7.0 Nil 12 54 102 8
Circulating water 8.5 14 70 504 1217 40
Observations: ¾ Cooling tower ‐1 is having low effectiveness compared to Cooling Tower‐2 ¾ CT ‐1 range found to be 7.9 and CT‐2 range found to be 11.6 against design of 8
Page 29
¾ CT‐1&2 approach found to be 10.73 and 8.8 against design 4 indicates, low ambient temp and poor heat transfer. ¾ CT‐1 &2, effectiveness found to be 42.40% and 56.86% against design 66.66%. which indicates poor heat transfer in CT ¾ Power measurement indicate under loading on CT fan motors and power factor is in the range of 0.52 to 0.74. This is poor. ¾ In Cooling Tower ‐1, Fly ash & other foreign particles are presented in reasonable quantity at most of the places like lowers, frills etc. ¾ Regarding cooling water circulation pumps observations and recommendations are made in chapter on pumps. ¾ As per the water quality concerned, makeup water quality is very good, here the scaling chances in the system are very less but corrosion is taking place aggressively specially in MS pipelines. ¾ At some places in cooling water piping system corrosion observed due to which water leakage/seepage is existing. ¾ As metal used in the cooling system are MS & Admiral brass so corrosion due to Chloride is not possible as it attacks only against SS metal, also the Chlorite level in circulating water is not very high for any trouble, with such metals (MS &AB) system may be run upto 2000ppm chloride level in the circulating water. ¾ Water in contact with metal surface sets up an electrolytic cell where by metal undergoes slow but steady dissolution. The metal is constantly oxidized to the metal oxide in presence of water with its dissolved oxygen, unless controlled properly. ¾ The corrosion in the system is due to improper functioning of corrosion inhibitor treatment. As PH in circulating water is around 8.5, Zn as corrosion inhibitor will not work perfectly at higher PH. As Zinc will precipitate at higher PH & not inhibit the surfaces perfectly. So organic treatment will be a good option for corrosion control. ¾ Alkalinity in the makeup water is very less; treatment philosophy must be designed to take care of low alkalinity system to control corrosion.
6.4 Conclusion and recommendation:‐ ¾ For energy savings and better air flow consider replacement of Aluminium alloy cooling tower fan blades, with energy efficient FRP hollow fan blade. Refer table below for detail cost benefit analysis. ¾ Cooling tower fills needs to be checked for fill chocking and poor water distribution. Equal and uniform water flow to each cell to be ensured for proper distribution of water. This will improve effectiveness of CT. Improved CT performance will allow to stop one CT fan during cold weather conditions. ¾ Periodically clean plugged cooling tower nozzle ¾ Monitor approach, effectiveness and cooling capacity for continuous optimisation efforts, as per seasonal variations as well as load side variations. ¾ A good chemical treatment with proper monitoring of the system will overcome all the water related problems in the system. ¾ Corrosion rack must be installed on monthly basis to check corrosion rate (mpy) in the system. ¾ Also Fly ash & other foreign particles adding microbiological load to the cooling system , a side stream filter may be installed to remove suspended particles from cooling towers along
Page 30
with proper bio‐dispersant dosing & Chlorine Di‐Oxide treatment in place of using oxidizing/non oxidizing biocide. Table: Cost benefit analysis with proposed modification of cooling tower fans blade material Proposed Cooling Tower Fan System Parameters Present Fan Case‐1 Case ‐2 System With New Motor With existing motor Fan Specifications Replace Fan blade by EE Replace Fan blade by EE No. of Fans 3 FRP hollow fan Blades & FRP hollow fan Blades only EE Motors of proper rating and utilise existing motors No. of Blades per fan 9 8 8 Dia of Blade assembly 144” 144” 144’ Blade Material Cast Al alloy FRP hollow fan Blades FRP hollow fan Blades CT Fan Motor KW 30Kw 15 30 Required Motor 30KW 15 KW 15 KW With present motor 12 KW at 80% loading and efficiency projected motor Energy Consumption 18 Kw 95% efficiency motor load ‐ 15 KW Energy consumption per 432KWh 288Kwh 360 Kwh day Annual Energy Saving Nil 52560 Kwh 26280 Kwh Saving in recurring Energy cost per annum Nil 2,62,800 INR 1,31,400 INR (@Rs5/Kwh) For each set of Cost of New blade set 85,000/‐ INR for each set blades For each set of Simple pay back 4 months (118Days) 8 months (236Days) blades The payback period through saving of recurring energy cost and consumption reduction by new FRP hollow CT fan blades, for each set of fan blades replaced is 4months when FRP Hollow Fan blades are installed with new high efficiency motor and 8 months if only new set of FRP Hollow Fan blades are installed with existing motor.
Page 31
7. ELECTRICAL SYSTEM & MOTORS
7.1
Background
Different types of electrical motors are used in a power plant to drive the various equipments like: ¾ Pumps ¾ Coal handling equipments ¾ Fans ¾ Crushers ¾ Blowers ¾ Others These motors and connected equipments consume significant amount of energy, which contributes to auxiliary power consumption. The auxiliary power consumption of this plant varies from 7.25% to 9% during the different months.
Electrical system and Motors 7.2
TRANSFORMERS
The facility is having two transformer which are installed to step down the 6.6 KV voltage supply generated by 4.4 MW transformer.
The transformers at Magnum Ventures Limited are naturally oil cooled. They are provided with Manual Off‐load Load Tap Changer. The 2000 KVA transformer is plinth mounted and 6500 KVA transformer is mounted at height.
OBSERVATION 1. There is no sub metering of the transformers. 2. The cumulative transformation capacity is 8500 KVA for 4300 MW (5625 KVA) Alternator. 3. The earthing pits are not adequately spaced.
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RECOMMENDATION 1. There is no sub metering of the transformers. It is highly recommended to install a sub meter on each of the transformer for monitoring the loading of the transformer. 2. The earthing pits provided are also not adequately spaced. This causes the earthing currents to either keep circulating in the system or is injected into the ground at various stages thus increasing heat losses. Due to this a major amount of energy which is produced is not recorded in the meters and a low efficiency is recorded. 3. The proper earthing also enhances the protection relays to function as per the design parameters and will improve system safety and reliability.
7.3
POWER FACTOR ANALYSIS
The primary purpose of the capacitor is to reduce the maximum demand. The additional benefits can be derived by capacitor location. Maximum benefit of capacitor is derived by locating them close to the load. In this way the KVAr are confined to the smallest possible segment, decreasing the load current. This reduces the power losses of the system substantially. The overall power factor of the plant is being maintained at above 0.93 lagging, but the power factor of some of the individual feeders is below the satisfactory level as given in the following bar chart.
OBSERVATION
1. The installed power factor compensating capacitors through ensures an overall good PF, since they are concentrated in few panels therefore the lagging currents are circulated in the whole distribution and transmission system. Transmission losses of plant are the losses occurring in main transformers, H.T. Cables, Switch Gear etc. = 3 % (Of total yearly Consumption). Distribution losses of plant are the losses occurring in main L.T. Cables, L.T. Switch Gear, L.T. Bus ‐Bar etc. = 7 % (Of total yearly Consumption)
Page 33
The following feeders were monitored using 3 phase power analyzer and the tentative savings at Rs. 3 per unit has been calculated for the purpose of payback period. Table: Annual Monetary Losses due to plant Distribution and Transmission Losses
Annual Monetary Losses due to plant Distribution and Transmission Losses Units generated at 0.8 PFL and availability
Units
4400 KW Generator
24107520
2200 KW Generator
12334080
Total units generated in KWH
36441600
Plant distribution losses and transmission losses (3%) in KWH
728832
Losses in monetary terms at Rs. 5/ unit
3644160
RECOMMENDATION 1. The installed capacitors need to be tested and relocated so that the plant transmission and distribution losses are reduced. The expected annual savings are Rs. 36, 44,160. Table: Capacitors installation Pay Back Period Calculations
Simple Pay Back Period Calculations Total load of the feeders
1358.5 KW
Average PF of the individual feeders Improved PF KVAr required
0.75 lagging 0.95 lagging 749.892 KVAr
Investment needed Simple Pay Back
Rs. 3,59,948.16 1.2 months
7.4
LOADING PATTERNS OF MOTORS
The motors are designed to run at maximum efficiency when they are loaded more than 60%. The power factor of the motors also decreases drastically when the motor is under loaded. Similarly, in the over loaded condition the efficiency, power factor, heating i.e. overall performance of the motor decreases. Therefore, it becomes one of the various criterions to evaluate the motor performance. This not only helps improving the efficiency as well as takes helps in the right selection of the motor capacity. The loading pattern of the plant motors is given in following table.
Page 34
Table: Loading pattern of plant motors
OBSERVATION 1. The following motors are operating at less than 60% loading. ID Fan motor loading is being optimized with the help of VFD. Table: List of motors operating at less than 60% loading
Page 35
RECOMMENDATION 1. The following motors are recommended to be changed with the lower capacity and efficient motors. Table: List of motors recommended for replacement with the lower capacity and energy efficient motors.
The Pay Back period of the motors has been included in the motor efficiency section of the report.
7.5
MOTOR EFFICIENCY
There are 48 motors in the power plant of capacity more than 3.5 HP. In all the operating parameters of 25 motors were successfully measured. There efficiency was calculated with the help of the measured and design data. The results are presented in the following table.
Motor Efficiency Calculation
Page 36
Table: Power Plant Motor efficiency
RECOMMENDTIONS After calculating the efficiency and monitoring the motor loading, the following motor have been suggested to be replaced with optimum capacity efficient motors. The annual savings in KWH and monetary terms has been calculated to determine the pay back period of each of the motor.
Page 37
Table: Techno economic analysis for replacement suggested motors
The total investment to replace the above mentioned motors is Rs. 6, 77,700 The cumulative annual saving in energy is 681959 KWH The cumulative monetary saving is Rs. 34, 09,797 The cumulative simple pay back period is 3 months
7.6 HARMONIC ANALYSIS We have measured Harmonic Level in the plant and results are mentioned as under. Table: Harmonic Measurement of Main Feeders
Page 38
OBSERVATION 1. The average total voltage harmonic distortion is 6.45%. 2. The average total current harmonic distortion is 9.3%. Table: Harmonics Measurement of Motors Sno.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 29 30 31 32 33 34 35 38 39 40
Description of Motor
FD Fan ID Fan Boiler FP 1 Boiler FP 2 Coal crusher 1 Coal crusher 2 Main elevator 1 Main elevator 2 Belt conveyor Reject elevator 1 Reject elevator 2 Submersible pump 1 Submersible pump 2 Submersible pump 3 Ash handling motor PA Fan HP 2‐1 RO HP 1‐1 RO HP 1‐2 RO HP 2‐2 RO Top screw 1 2.2 MW CT Pump 1 2.2 MW CT Pump 2 2.2 MW CT Pump 3 2.2 MW CT Fan 1 2.2 MW CT Fan 2 2.2 MW CT Fan 3 2.2 MW CEP 1 4.4 MW CT Fan 1 4.4 MW CT Fan 2 4.4 MW CT Fan 3
Voltage Harmonics
Current Harmonics
3rd
5th
7th
THD
3rd
5th
7th
THD
0 0 0 0 0 0 0 0 0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
22.4 22.5 20.9 19.7 15.3 14.7 15 5.3 14.2 22 23.1 8.3 25.1 19.7 18.8 16.3 15.8 16.8 14 5 5.4 5.2 5.2 4.7 4.6 4.5 20.1 18.1 15.6
7.7 6.1 7.4 4.6 6.1 6 1.2 1.2 4.1 7 6.3 4.8 11.6 7.5 7 6.1 5.3 7.2 6.1 1.4 0 0 3.1 0 3.1 0 5.7 5.5 7
8.6 6.5 6.2 5.3 3.8 5 5.3 5.6 20 5.9 5.6 2.6 7.6 6.4 6.1 4.5 4.3 4.3 4.1 5.7 1.3 1.5 1.5 1.4 1.4 1.4 5.3 4.8 4
21.8 4.8 18.1 5.2 0.3 0 0 1.1 4.1 22 0.3 0.5 0.7 0.4 6.7 0.3 0.3 0.4 0.3 2.2 0 0.3 0.4 0 0.4 0 0.8 1.5 0.8
72.9 22.5 69 21.1 1.6 2.2 0.9 9.5 9.7 30 1.5 0.7 3.7 0.8 16.7 1.9 1.8 1.6 1 12.4 0.4 0.5 0.8 0.8 0.6 0.5 3.5 3.2 2.9
27.7 11.4 22.5 6.5 0.8 0.5 0.3 2.1 3.1 15.5 0.3 1.2 1.4 0.4 6.1 0.6 0.4 0.6 0.5 2.2 0.3 0.4 0.4 8.4 0.4 0.3 1.3 0.6 1.5
52.6 47.7 9.6 9.7 8.3 9.9 9.5 10.8 13.2 45 3.8 3.7 10.4 12.6 43 8.2 7.2 8.5 7.5 16 1.2 2.6 3.9 3.6 3.8 2.9 14.8 13.4 10.8
OBSERVATION 1. The average total voltage harmonic distortion is 5.34%. 2. The average total current harmonic distortion is 13.59%.
Page 39
7.7 POWER SUPPLY QUALITY The BIS standard specifies that a motor should be capable of delivering its rated output with a voltage variation of 6%. The continuous voltage variation causes motors to heat up and thus triggering the deterioration of insulation system. The Power Factor, Slip and torque of the motor is also affected by the voltage variation. Table: Power supply quality and Voltage Variation
OBSERVATION 1. The variation between the terminal voltage and specified voltage is under 5% which is a healthy sign.
Page 40
REF - JCTE/09-10/29791
Dated : 26-06-2010
M/s Modinagar Paper Mills ltd. Modinagar U.P Sub : Quotation for FRP Fan Assembely for Cooling Tower. Kind Atten : Mr.Anubhav Gupta Dear Sir, We are receipt of your enquiry No –nil Dated :26-06-10 regarding requirement of FRP Fan Assembly for cooling tower . Now we are quoting our best.
SI. NO. 01.
DESCRIPTION OF ITEM FRP HOLLOW FAN BLADES COMPLETE WITH HUB . (Statically Balanced)
QTY
1Set of 8blades
UNIT RATE
AMOUNT
85,000/-
85,000.00
No. Of Blades -8 MOC of Blades – FRP Hollow type TERMS & CONDITIONS : Delivery : With in 2-3 Weeks after receipt of your P.O. Payment : 40% Payment along with P.O. and balance payment on submission of P.I Prior to dispatch. Sales Tax : 2% against form "c" Valadity : 30 Days. Packing & Forwarding Charges : Nil Freight Charges : Extra At Actual. Insurrance : By Customer. Guarantee : 1 year from the date of supply.
Thanking You Your"s Faithfully
For JITENDRA COOLING TOWER (ENGS)
Authorised Signatuory (J.D.Sharma) cell-9313784391
APPENDIX 1 What is Harmonics: At the time of the designing any A.C. machine, it is assumed that voltage and current wave from at the output terminals of A. C. machines is assumed to be sinusoidal and consists of only one frequency which is called fundamental frequency or 1st harmonics and such sinusoidal wave from dose not contain harmonics of other frequency. Due to non linear system load such as thyristorised control, variable frequency drive and D. C. motor, a harmonics are generated at the output side of the A.C. machines and hence original sinusoidal wave form are disturbed and wave form becomes complex and non sinusoidal in nature generating 2nd, 3rd, 4th and so on frequencies of the fundamental frequency. The above phenomenon is shown in the below given diagram. These 2nd, 3rd, 4th frequencies are called harmonics of the fundamental frequency. In short waveform with frequencies other than fundamental frequency is called harmonics. 2nd, 4th etc frequencies are called even harmonics and 3rd, 5th, 7th, etc frequencies are called harmonics.
Harmonics in transformer:The non‐sinusoidal nature of the magnetizing current necessary to produce a sine wave of flux produces harmonics in current and voltage wave –forms of the three phase transformers. The effects of current harmonics:‐ 1. Increased heating of winding. 2. Inductive interference with communication circuits. 3. Increased iron losses. The effects of voltage harmonics:a) Increased heating of winding. b). Capacitive interference with communication circuits. c). Production of large resonant voltages.
Major Causes of Harmonics Devices that draw non‐sinusoidal currents when a sinusoidal voltage is applied create harmonics. Some of these devices are listed below: Electronic Switching Power Converters 1. Computers, UPS, Solid‐state rectifiers. 2. Electronic process control equipments 3. Electronic Lightning Ballasts. ‐ 1 ‐
4. Reduced voltage motor controllers. Arcing Devices 1. Discharge lighting. 2. Arc furnaces, welding equipments. Ferromagnetic devices. 1. Transformers operating near saturation level. 2. Magnetic ballasts. 3. Induction heating equipment chokes. Appliances 1. TV sets air conditioners, washing machines, and microwave ovens. 2. Fax machines, photocopiers, and printers. Higher RMS current and voltage in the system are caused by harmonic currents, which can result in any of the problems listed below: 1. Blinking of Incandescent Lights‐ Transformer Saturation. 2. Capacitor Failure‐ Harmonic Resonance. 3. Circuit Breakers Tripping‐ Inductive Heating and Overload. 4. Electronic Equipment Shutting down‐ Voltage Distortion. 5. Flickering of Fluorescent lights‐ Transformer Saturation. 6. Fuses Blowing for no apparent reason‐ Inductive heating and Overload. 7. Motor Failures (overheating) – Voltage Drop. 8. Conductor Failure‐ Inductive heating. 9. Neutral conductor and terminal failures – Additive Triplen currents. 10. Electromagnetic Load Failures – Inductive heating. 11. Overheating of Metal Enclosures‐ Inductive heating. 12. Power Interference on voice communication‐ harmonic noise. 13. Transformer failures‐ Inductive Heating.
Overcoming Harmonics Tuned Harmonics filters consisting of a capacitor bank and reactor in series are designed and adopted for suppressing harmonics by providing low impedance path for harmonic component. The harmonic filters connected suitably near the equipment generating harmonics help to reduce THD to acceptable limits. For overcoming and troubleshooting of some problems in the electrical power system ‐ 2 ‐
HARMONICS WAVE FORM
‐ 3 ‐
APPENDIX 2 Power factor improvement with the use of static capacitors:‐ In case of alternating current power supply system current is always lag behind the voltage. This is due to the fact that the A.C. machines works on the principle of electromagnetic induction and these A.C. machines consume reactive power for their own needs for formation of magnetic flux and this phenomenon will cause current vector to lag behind the voltage vector and this will generates the P.F. in the system. The above fact is shown in below sine wave diagram.
What is Power Factor:‐ The P. F. = CosØ is the ratio of KW = Active Power KVA Apparent Power Methods of improving power factor:1. With the use of static capacitors. 2. With the help of synchronous condenser. 3. With use of phase advancers. ‐ 4 ‐
Here we can discuss the use of static capacitor and there advantages for improving How Power factor improves with the use of static capacitors:‐ The static capacitor generates reactive current of opposite nature at leading power factor when connected to the supply mains parallel to inductive load and compensates reactive current of the inductive load, which is running at lagging power factor. ∴ When static capacitor is connected parallel to the inductive load, the inductive load starts receiving reactive power of opposite nature at leading power factor from the capacitors and thus this reactive power neutralizes the inductive power requirement of the load and thereby improves the P. F. of the load. The above Explanations are made simple with the below mentioned Vector Diagram.
The P. F. = CosØ is the ratio of KW = Active Power KVA Apparent Power
Vector diagram and physical diagram of inductive load with use of capacitor
‐ 5 ‐
Effect of Different Power Factor on 100 KW Industrial Motor Working Load:
Assume 3 phase, 100 KW rating inductive motor., V = 415, P.F. = Cos ↓ = Cos 0° = 1, ∴↓ = 0°, F = 50 HZ, Efficiency = 90 % Sin ↓ = Sin 0° = 0 η Of Motor = Output Input = 1.73 x V x I x Cos ↓ = output x 100 Input η I = 100 x1000 1,73 x 415 x1 x 0.90 I (line) = 155 Amp. Active Current = I active = I(line) x Cos ↓ = 155 x 1 = 155 Amp. Reactive Current = I reactive = I(line) x Sin ↓ = 155 x 0 = 0 Amp. The KVA = KW = 100 =100 KVA Cos ↓ 1 KW = KVA x Cos ↓ = 100x1 = 100
‐ 6 ‐
KVAr = KVA x Sin ↓ = 100x0 = 0
Vector Diagram
Active Power – (KW) = 100
Reactive power‐(KVAr) = 0 Apparent or resultant power – (KVA) = 100 (B) 100 KW load working at Cos ↓ = P. F. =0.90, ∴↓ = 25° The KVA = KW = 100 = 111 KVA Cos ↓ 0.90 Line Current = I (line) at P.F of 0.90 = 155 Amp./ 0.90 = 172 Amp Active Current = I active = I(line) x Cos ↓ = 172 x 0.90 = 155 Amp Reactive Current = I reactive = I(line) x Sin ↓ = 155 x 0.422 = 64.4 Amp. KW = KVA x Cos ↓ = 111x0.90 = 100 KVA = 111 KVAr = KVA x Sin ↓ = 111x0.422 = 47 : Vector Diagram : Active power – (KW) = 100 KW ↓ = 25° Voltage vector ‐ V
Current vector – A . Reactive power–(KVAr) = 47
Apparent or resultant power – (KVA) = 111
(C) 100 KW load working at Cos ↓ = P. F. = 0.80, ∴↓ = 36.8° Line Current = I (line) at P.F of 0.90 = 155 Amp./ 0.80 = 194 Amp Active Current = I active = I(line) x Cos ↓ = 194 x 0.80 = 155 Amp ‐ 7 ‐
Reactive Current = I reactive = I(line) x Sin ↓ = 194 x 0.599 = 116 Amp The KVA = KW = 100 = 125 KVA Cos ↓ 0.80 KW = KVA x Cos ↓ = 125x0.80 = 100 KVA = 125 KVAr = KVA x Sin ↓ = 125x0.599 = 75
: Vector Diagram :
Active power – (KW) = 100 KW ↓ = 36.8° Voltage Vector ‐ V Reactive power–(KVAr) = 75 Current vector ‐ A Apparent resultant power – (KVA) = 125
From the above vector diagrams and below mentioned calculation it can be seen that at (A) 100 KW load and P. F. = 1 ∴KVA = 100 KVA ∴ Demand charges = 100 x Rs.200 = Rs.20000/‐ (Assuming Demand Charges = Rs. 200 /KVA) (B) 100 KW load and P. F. = 0.90 ∴KVA = 111 KVA ∴ demand charges = 111 x Rs. 200 = Rs.22200/‐ ‐ 8 ‐
APPENDIX 2A Methods of testing & checking of capacitors:‐ •
With the help of AVO meter ‐ A good capacitor will show dead short between any two terminals first & then charge up to battery voltage.
•
Megger test‐ A good capacitor will show infinity resistance between any terminals & earth.
•
With the help of Ampere meter ‐ A good capacitor will draw rated current at rated voltage.
We suggest checking the APFC capacitor current ratings, every week and replacing any faulty capacitors as soon as possible. Importance of good Power Factor and various benefits thereof: ‐ 1. The KW capacity of the prime movers is better utilized. 2. The KVA capacity of the transformers and cables are increased. 3. The efficiency of every plant is increased. 4. The overall production cost per unit decreased. 5. Heat losses in any electrical machine = k x 1/P.F. and hence high P. F. will generate less heat.
6. Reduction of plant electrical losses due to improvement of P. F. = 1 7. KVA reduction =
Disadvantages of poor power factor: ‐ 1. Losses in any electrical equipment are proportional to i² which means proportional to 1/P.F.² thus losses at P.F. = Unity = 1 and losses at P.F. = 0.8 are 1/ [0.8] ² = 1.57 times higher than those at unity P. F.
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2. Rating of motors and transformers etc. are proportional to current hence to 1/P. F. therefore large motors and transformers are required. 3. Poor P. F. causes a large voltage drop, hence extra regulation equipment is required to keep voltage drop within prescribed limits.
Indirect benefits of improved P. F.:- (Example for understanding) 1. Losses reduction of the plant due to improvement in P. F. from P. F. 1 (0.92) to P. F. 2 (0.98) Now we are raising the existing P. F. of 0.92 to new P. F. of 0.98. Therefore, monthly energy loss reduction in the plant, due to improvement of PF
= 1
= 1
. .
= 1 – 0.8812 = 0.1188 = 11.88 % When current I amperes flow through any electrical machines having resistances R ohms for t seconds the electrical energy expended is I² x R x t joules. ∴Heat produced = I² x R x t / 4187 kilocalories. ∴Heat produced at PF 1 (0.92) = k [1/ (PF 1)2] & Heat produced at PF 2 (0.98) = k [1/(PF 2)2] ∴Reduction in heat generation due to improvement of P. F.
=
= k x [ 1.1814 – 1.0412 ] = k x 0.1402 Calories
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APPENDIX 3 Motor Efficiency Test (No Load Method) We have taken measurement 10 HP motor for calculation of efficiency. Motor Specifications Rated power = 7.5 kW/10 HP Voltage = 415 Volt Current = 17 Amps Speed = 935 RPM Connection = Delta No load test Data Voltage, V = 424 Volts Current, I = 5.9 Amps Frequency, F = 50 Hz Stator phase resistance at 20 °C = 2.5 Ohms No load power, Pnl = 156 Watts ( a) Let Iron Plus Friction and windage Loss , Pi + fw No load Power Pnl – 156 Watt o
Stator copper Loss, Pst @ 20 C (Pst.Cu) = 3 x (5.9/1.73) 2 x 2.5 = 87.23 Watt Now Pi + fw = Pnl – Pst.cu = 156 – 87.23 = 68.77 Watt (b) Stator Resistance at 120 C 2.5
3.48
0
(c) Stator Copper Losses at Full Load Pst.cu 120 C = 3 x (17/1.73) 2 x 3.48 = 1008.32 Watt ‐ 11 ‐
(d) Full Load Slip =
= 0.065
Thus, Input to Rotor =
. .
= 8021.40 (e) Total Full Load Input Power = 8021.40 + 1008.32 + 68.77 + 37.5 ( stray Losses 5 % of rated Output) = 9135.99 Watt Say 9136 watt (E) Motor efficiency at Full Load =
= 82.09 % say 82 % Above test clearly shows that Old and many times rewind Motors have very low efficiency as compared to new Energy efficient Motor. New Energy Efficient Motors have efficiency up to 95%. So you are advised to avoid the use of old rewound motors or motor with stated efficiency of less than 90% on test certificate in future. Above motors have total measured running load as 463.75 KW and average efficiency of 83.6%. Replacement of motors can bring the efficiency of 95% on running load thus improving efficiency by 11.4% and subsequently reducing the load by 52.86 KW. This will result in savings of 52.86 x 20 hrs per day x 30 days = 31716 KWH each month = 31716 x 4.19 = INR 1,32,890 each month ‐ 12 ‐
Tentattive investtment of 4 410.88 KW W = 410.88 8 x 2700 per KW = IN NR 11,09,382 Salvagge Value off old moto ors = 400 xx 463 KW = INR, 1,8 85,200 Thus n net investm ment = 11 109382 – 1 185200 = IINR 9,24,1 182 Hence simple paayback = 9 924182/13 32890 = 6.95 say 7 Months. We recommend d use of Baldor mottors which h are NEM MA Premiu um efficiency rangee motors and maintain veryy high efficiency eveen at 25% loading.
wer Stag ges In An n Inducttion Motor: : Pow
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Variation of Motor Efficiency /P. F / Stator Current / Torque & Speed
with receipt to Load Demand
Power Loss Due to Under Load Operation of Induction Motor (% of Power Loss in Motor): Whenever induction motors runs in under load conditions, heavy power losses are observed and hence under loading and no load running of the inductions motor are to be avoided. For our customers knowledge a following chart of power losses is attached. Power Loss Due to Under Load Operation of Induction Motor (% of Power Loss in Motor) :
Motor Capacity in H.P. 5 7.5 10 15 20 25 30 40 50 60 75 100
No Load
25 % Load
50 % Load
Full Load
50 45 44 43 42 41.5 41 40 40 39 38.5 38
40 30 26 23 20 19 18 17 16 15.5 13 13
25 20 18 17 15 15 14 15.5 12.5 12.5 12 12
18 17 17 14 14 13 13 10.5 10 10 9 9
Motor (HP) 5 7.5 10 15 20 25 30 40
Rating Capacitor rating (kVAr) for Motor Speed 3000 1500 1000 750 2 2 2 3 2 2 3 3 3 3 4 5 3 4 5 7 5 6 7 8 6 7 8 9 7 8 9 10 9 10 12 15
600 3 4 5 7 9 9 10 16
500 3 4 6 7 10 12 15 20 ‐ 14 ‐
50 60 75 100 125 150 200 250
10 12 15 20 25 30 40 45
12 14 16 22 26 32 45 50
15 15 20 25 30 35 45 50
18 20 22 26 32 40 50 60
20 22 25 32 35 45 55 65
22 25 30 35 40 50 60 70
Table – Rating of Capacitor required for different rating and speed.
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APPENDIX 4 Performance Evaluation of Motors Electrical motors accounts for a major part of the total electrical consumption. So a careful attention should be given to the performance of this utility. Measurements of the different electrical parameters of the major motors of the plant are given in Table The efficiency of the induction motor and loading condition of the motors are directly proportional to each other. Higher the loading and higher is the efficiency of the motors. The best efficiency of the motors is achieved at a load very much near to the rated load. Moreover at lower loads the power factor is on the lower side increasing the load current and thereby increasing the copper losses, resulting in lower efficiency, the rating of the motors should be decided after carefully understanding the process requirement in the absence of which the motor might come out to be oversized. Also one should run a motor, which has been rewound more than once as every time a motor is rewinded it losses 2 – 5% of its actual efficiency. Motor performance is affected considerably by the quality of input power that is the actual volts and frequency available at motor terminals, vis‐à‐vis rated values as well as voltage and frequency variations and voltage unbalance across the three phases. Mostly all the motors are old or rewound at least once. A good saving can be achieved if higher efficient ones replace them. Though it’s a scheme with higher initial investment but can be implemented phase wise. Induction motors are characterized by power factors less than unity, leading to lower overall efficiency (and higher overall operating cost) associated with a plant’s electrical system. Capacitors connected in parallel (shunted) with the motor are typically used to improve the power factor. The impacts of PF correction include reduced KVA demand (and hence reduced utility demand charges), reduced I2R losses in cables
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(leading to improved voltage regulation), and an increase in the overall efficiency of the plant electrical system. It should be noted that PF capacitor improves power factor from the point of installation back to the generating side. It means that, if a PF capacitor is installed at the starter terminals of the motor, it won’t improve the operating PF of the motor, but the PF from starter terminals to the power generating side will improve, i.e., the benefits of PF would be only on upstream side. The size of capacitor required for a particular motor depends upon the no‐load reactive KVA (KVAR) drawn by the motor, which can be determined only from no‐ load testing of the motor. Higher capacitors could result in over‐voltages and motor burnouts. Alternatively, typical power factors of standard motors can provide the basis for conservative estimates of capacitor ratings to use for different size motors.
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APPENDIX 4A We are suggesting some Measures to Improve Efficiency of Motors and Distribution system 1: Electrical Distribution Correction Measures available to improve power quality and reduce electrical losses are 1. Maintain voltage level close to nameplate level as far as possible, with a maximum deviation of 5% (at 5% under voltage, copper loss is increased to 10%). 2. Minimize phase imbalance within a tolerance of 1%. As deviation of one phase voltage from average phase voltage increases, it will result in increased winding temperature. 3. Maintain high power factor to reduce distribution losses. 4. Avoid excessive harmonic content in the power supply system, as increased harmonic content in power supply system will increase motor temperature. 5. Use oversize distribution cable in the new installation to reduce copper losses. This will also help in reducing voltage drop during starting and running and minimizing the motor losses. 2: Motor Efficiency Improvement The measures available to improve motor efficiency are: 1. If motor is running at partial load then convert motor from delta to star connection. This will improve motor efficiency. 2. Replace rewound induction motor (with reduced efficiency) with new energy efficient motor. 3. If process demands oversized motor then possibility of use of VFD may be explored to save energy. This is also applicable in case of varying load duty cycle motor application. 4. Control the motor drive temperature. This will reduce copper losses and increase motor life. ‐ 19 ‐
3: Better System Matching Measures available are: 1. Use an on/off control system using timer, PLCs, etc to provide motor power only when required. 2. Size the motor to avoid insufficient low load operation. Motor should run at 65% to 95% of its nameplate rating to get maximum efficiency. 4: Driven Load and Process Optimization Measures available to optimize the process and its operation are: 1. Change or reconfigure the process or application so that less input power is required. 2. Downsize the over sized pumps, fans, compressors or other driven loads if possible. 3. Install more efficient mechanical subsystems. Check that coupling, gearbox fan or pump must be energy efficient. Miscellaneous Measures to Improve Motor Efficiency
Maintenance Energy savings of 10 to 15 percent of motor energy consumption can typically be realized, depending on change from existing maintenance practices. These are: 1. Proper lubrication: it will minimize wear on moving parts. Lubrication is best done on a regular schedule to ensure wear is avoided. Once it occurs, no lubricant can undo it. It is crucial that the correct lubricant is applied in the right quantities. 2. Correct shaft alignment: It ensures smooth, efficient transmission of power from the motor to the load. Incorrect alignment puts strain on bearings and shafts, shortening their lives and reducing system efficiency. Shafts should be parallel and directly in line with each other. It is necessary to use precision instruments to achieve this. Shaft alignment is an important part of installation and should be checked at regular intervals. 3. Proper alignment: Belts and pulleys must be properly aligned and tensioned when they are installed, and regularly inspected to ensure alignment and ‐ 20 ‐
tension stay within tolerances. Abnormal wear patterns on belts indicate specific problems that may require correction. Loose bests may squeal and will slip on the pulleys, generating heat. Correctly tensioned pulleys run cool. Excess tension strains bearings and shafts, shortening their lives. 4. Painting of motor: Avoid painting motor housing because paint acts as insulation, increasing operating temperatures and shortening the lives of motors. One coat of paint has little effect, but paint buildup accumulated over years may have a significant effect.
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APPENDIX 5 Maintenance Schedule of MOTOR for Energy Conservation i). Daily: ‐ Clean the motor and starter. ii). Weekly: ‐ Clean slip rings with soft brush dipped in white spirit. iii). Monthly: ‐ Check earth connections of motor and starter. Blow through motor and starter with dry compressed air at 2 Kg/Cm2 . Check tightness of cable connections. Check motor for overheating and abnormal noise / sound, sparking and for proper bedding of brushes. Tighten belts and pulleys to eliminate excessive losses. iv). Quarterly: ‐ Check motor terminal voltage for balanced supply. If more than +1% of average, then check from transformer onward. Carry out SPM checks viz. vibrations and sound of bearing. Record reading and compare With earlier / other motor readings. Slip Ring: ‐ Inspect the brushes and make sure that they move freely in the brush holder clips. Clean brushes, holder chip and wipe with cloth dipped and in gasoline. Replace the brush if they are worn out less than 5 mm in length from brush holder. Clean the starter and motor contacts with white spirit. v). Six Monthly Maintenance: ‐ Check over load mechanism of starter. Check alignment of motor with driven equipment. Check no load current and compare with earlier / original. Check / change lubrication as per lubrication schedule given on next pages. Check the securing foundation nuts for tightness. Inspect the paint coating and do‐touching wherever required. Check IR(Insulation) Resistance of motor and starter with 500 V megger. It should be more than 2 MΩ
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